{"id":17653,"date":"2026-07-17T21:21:52","date_gmt":"2026-07-17T12:21:52","guid":{"rendered":"https:\/\/genai-ai.co.jp\/ai-kanri\/?p=17653"},"modified":"2026-07-17T21:21:52","modified_gmt":"2026-07-17T12:21:52","slug":"cc-javascript-date-compare-3","status":"publish","type":"post","link":"https:\/\/genai-ai.co.jp\/ai-kanri\/blog\/cc-javascript-date-compare-3\/","title":{"rendered":"\u30102026\u5e747\u6708\u6700\u65b0\u3011JavaScript\u306e\u65e5\u4ed8\u53d6\u5f97\u30fb\u6bd4\u8f03\u30fb\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u5b8c\u5168\u30ac\u30a4\u30c9\uff5cDate()\u306e\u4f7f\u3044\u65b9\u304b\u3089Claude Code\u6d3b\u7528\u307e\u3067"},"content":{"rendered":"\n<style>\n.g-flow-row{display:flex;gap:8px;justify-content:center;flex-wrap:wrap;align-items:center;}\n.g-flow-item{background:linear-gradient(135deg,#1a1a1a,#2a1015);color:#fff;border-radius:8px;padding:16px 14px;min-width:130px;flex:1;text-align:center;}\n.g-flow-arrow{color:#dc2626;font-size:20px;font-weight:700;}\n.g-card-row{display:flex;gap:12px;flex-wrap:wrap;margin:0 0 32px;}\n.g-card-row>div{flex:1;min-width:220px;}\n@media(max-width:600px){\n  .g-flow-row{flex-direction:column;}\n  .g-flow-arrow{transform:rotate(90deg);}\n  .g-card-row{flex-direction:column;}\n  .g-card-row>div{min-width:100%;}\n}\n<\/style>\n\n\n\n<div style=\"margin:0 0 32px;\">\n  <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/07\/thumb-cc-javascript-date-compare-2.jpg\" alt=\"\u30102026\u5e747\u6708\u6700\u65b0\u3011JavaScript\u306e\u65e5\u4ed8\u53d6\u5f97\u30fb\u6bd4\u8f03\u30fb\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u5b8c\u5168\u30ac\u30a4\u30c9\uff5cDate()\u306e\u4f7f\u3044\u65b9\u304b\u3089Claude Code\u6d3b\u7528\u307e\u3067\" style=\"width:100%;height:auto;border-radius:12px;display:block;\">\n<\/div>\n\n\n\n<div style=\"background:#f8f9fa;border-radius:12px;padding:24px 28px;margin:0 0 32px;border-left:4px solid #dc2626;\">\n  <p style=\"font-size:15px;font-weight:700;color:#1a1a1a;margin:0 0 16px;\">\u3053\u306e\u8a18\u4e8b\u306e\u5185\u5bb9<\/p>\n  <ol style=\"margin:0;padding-left:20px;font-size:14px;line-height:2.2;list-style:none;\">\n    <li><a href=\"#sec-01\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">01<\/span>JavaScript\u306eDate\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u57fa\u672c\uff1a\u73fe\u5728\u65e5\u6642\u306e\u53d6\u5f97\u3068\u4e3b\u8981\u30e1\u30bd\u30c3\u30c9<\/a><\/li>\n    <li><a href=\"#sec-02\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">02<\/span>\u65e5\u4ed8\u306e\u6bd4\u8f03\u65b9\u6cd5\uff1agetTime()\u30fb\u6bd4\u8f03\u6f14\u7b97\u5b50\u306e\u4f7f\u3044\u65b9<\/a><\/li>\n    <li><a href=\"#sec-03\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">03<\/span>\u65e5\u4ed8\u5dee\u306e\u8a08\u7b97\uff1a\u65e5\u6570\u30fb\u6642\u9593\u30fb\u5206\u306e\u30df\u30ea\u79d2\u8a08\u7b97<\/a><\/li>\n    <li><a href=\"#sec-04\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">04<\/span>\u65e5\u4ed8\u306e\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\uff1aYYYY-MM-DD\u30fb\u65e5\u672c\u8a9e\u5f62\u5f0f\u306b\u5909\u63db<\/a><\/li>\n    <li><a href=\"#sec-05\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">05<\/span>\u3088\u304f\u3042\u308b\u30d0\u30b0\u3068\u843d\u3068\u3057\u7a74\uff1a\u6708\u306f0\u59cb\u307e\u308a\u30fb\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u554f\u984c<\/a><\/li>\n    <li><a href=\"#sec-06\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">06<\/span>\u5b9f\u7528\u7684\u306aDate\u6d3b\u7528\u30d1\u30bf\u30fc\u30f3\uff1a\u6628\u65e5\u30fb\u660e\u65e5\u30fbN\u65e5\u5f8c\u306e\u8a08\u7b97<\/a><\/li>\n    <li><a href=\"#sec-07\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">07<\/span>Claude Code\u3067\u65e5\u4ed8\u51e6\u7406\u30d0\u30b0\u3092\u30c7\u30d0\u30c3\u30b0\u3059\u308b\u65b9\u6cd5<\/a><\/li>\n    <li><a href=\"#faq\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">FAQ<\/span>\u3088\u304f\u3042\u308b\u8cea\u554f<\/a><\/li>\n  <\/ol>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">JavaScript\u306e\u65e5\u4ed8\u64cd\u4f5c\u306f\u300c\u7c21\u5358\u306a\u3088\u3046\u3067\u843d\u3068\u3057\u7a74\u304c\u591a\u3044\u300d\u9818\u57df\u3067\u3059\u3002\u300c\u6708\u306f0\u59cb\u307e\u308a\u300d\u300c\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u306e\u6271\u3044\u300d\u300c\u6587\u5b57\u5217\u3092==\u3067\u6bd4\u8f03\u3057\u3066\u3057\u307e\u3046\u300d\u306a\u3069\u3001\u7d4c\u9a13\u8005\u3067\u3082\u30cf\u30de\u308b\u30d0\u30b0\u304c\u591a\u3044\u3067\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u8a18\u4e8b\u3067\u306f<strong>Date()\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u30fb\u65e5\u4ed8\u306e\u6bd4\u8f03\u30fb\u65e5\u4ed8\u5dee\u306e\u8a08\u7b97\u30fb\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u5909\u63db\u30fb\u3088\u304f\u3042\u308b\u30d0\u30b0\u30d1\u30bf\u30fc\u30f3<\/strong>\u3092\u5b9f\u969b\u306e\u30b3\u30fc\u30c9\u4f8b\u4ed8\u304d\u3067\u89e3\u8aac\u3057\u307e\u3059\u3002\u5f8c\u534a\u3067\u306fClaude Code\u3092\u4f7f\u3063\u305f\u65e5\u4ed8\u51e6\u7406\u30d0\u30b0\u306e\u30c7\u30d0\u30c3\u30b0\u52b9\u7387\u5316\u3082\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<div class=\"balloon-wrap\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/ceo-sugasawa.jpg\" alt=\"\u4ee3\u8868\u83c5\u6fa4\">\n    <span class=\"balloon-name\">\u4ee3\u8868\u83c5\u6fa4<\/span>\n  <\/div>\n  <div class=\"balloon-body\">\u300cJavaScript\u306e\u65e5\u4ed8\u306e\u6708\u306f0\u59cb\u307e\u308a\uff080=1\u6708\u300111=12\u6708\uff09\u300d\u3068\u3044\u3046\u4ed5\u69d8\u306f\u3001JavaScript\u5b66\u7fd2\u8005\u304c\u6700\u521d\u306b\u9a5a\u304f\u7f60\u306e\u3072\u3068\u3064\u3067\u3059\u3002\u3053\u306e\u4ed5\u69d8\u3092\u77e5\u3089\u306a\u3044\u3068\u8868\u793a\u3055\u308c\u308b\u6708\u304c\u5e38\u306b1\u30f6\u6708\u305a\u308c\u308b\u30d0\u30b0\u304c\u767a\u751f\u3057\u307e\u3059\u3002\u307e\u305a\u3053\u3053\u3092\u62bc\u3055\u3048\u3066\u304a\u304d\u307e\u3057\u3087\u3046\u3002<\/div>\n<\/div>\n\n\n\n<div class=\"balloon-wrap is-right\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/yamazaki-avatar.png\" alt=\"AI\u9b3c\u7ba1\u7406\u5c71\u5d0e\">\n    <span class=\"balloon-name\">AI\u9b3c\u7ba1\u7406\u5c71\u5d0e<\/span>\n  <\/div>\n  <div class=\"balloon-body\">\u65e5\u4ed8\u306e\u300c\u6587\u5b57\u5217\u6bd4\u8f03 vs \u30df\u30ea\u79d2\u6bd4\u8f03\u300d\u306f\u5b9f\u52d9\u3067\u3088\u304f\u554f\u984c\u306b\u306a\u308a\u307e\u3059\u3002\u300c2024-03-01\u300d\u3068\u300c2024-11-15\u300d\u3092\u6587\u5b57\u5217\u3068\u3057\u3066\u6bd4\u8f03\u3059\u308b\u3068\u6587\u5b57\u30b3\u30fc\u30c9\u9806\u306e\u6bd4\u8f03\u306b\u306a\u308a\u3001\u591a\u304f\u306e\u5834\u5408\u306f\u6b63\u3057\u304f\u52d5\u304d\u307e\u3059\u304c\u3001\u300c2024-3-1\u300d\uff08\u30bc\u30ed\u57cb\u3081\u306a\u3057\uff09\u304c\u6df7\u5728\u3059\u308b\u3068\u8aa4\u3063\u305f\u7d50\u679c\u306b\u306a\u308a\u307e\u3059\u3002\u5e38\u306bgetTime()\u3067\u30df\u30ea\u79d2\u306b\u5909\u63db\u3057\u3066\u6570\u5024\u6bd4\u8f03\u3059\u308b\u3053\u3068\u3092\u304a\u52e7\u3081\u3057\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n\n<div style=\"background:#fafafa;border-radius:8px;padding:16px 20px;margin:16px 0;border-left:4px solid #dc2626;\">\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>Date()\u306e\u4e3b\u8981\u30e1\u30bd\u30c3\u30c9\u4e00\u89a7<\/strong>\uff08getFullYear\u30fbgetMonth\u30fbgetDate\u30fbgetTime\u7b49\uff09<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>\u65e5\u4ed8\u6bd4\u8f03\u306e\u6b63\u3057\u3044\u3084\u308a\u65b9<\/strong>\uff08getTime()\u3067ms\u5909\u63db\u30fb\u6bd4\u8f03\u6f14\u7b97\u5b50\u306e\u4f7f\u3044\u5206\u3051\uff09<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>\u65e5\u4ed8\u5dee\u306e\u8a08\u7b97\u5f0f<\/strong>\uff08\u65e5\u6570\u30fb\u6642\u9593\u30fb\u5206\u306e\u8a08\u7b97\u65b9\u6cd5\uff09<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>\u65e5\u4ed8\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u5909\u63db<\/strong>\uff08YYYY-MM-DD\u30fb\u65e5\u672c\u8a9e\u5f62\u5f0f\u30fbISO 8601\u5f62\u5f0f\uff09<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>\u6708\u306f0\u59cb\u307e\u308a\u306e\u7f60<\/strong>\u30fb\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u554f\u984c\u306e\u5bfe\u51e6\u6cd5<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>Claude Code\u3067\u65e5\u4ed8\u30d0\u30b0\u3092\u7d20\u65e9\u304f\u30c7\u30d0\u30c3\u30b0\u3059\u308b\u65b9\u6cd5<\/strong><\/span><\/div>\n\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-javascript-date-compare-3&#038;blog_slug=cc-javascript-date-compare-3\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-javascript-date-compare-3&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-01\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">01<\/span>\n  <span class=\"section-label\" style=\"display:block;\">DATE BASICS<\/span>\n  <span class=\"section-title\" style=\"display:block;\">JavaScript\u306eDate\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u57fa\u672c\uff1a\u73fe\u5728\u65e5\u6642\u306e\u53d6\u5f97\u3068\u4e3b\u8981\u30e1\u30bd\u30c3\u30c9<\/span>\n  <span class=\"section-desc\">new Date()\u304b\u3089\u59cb\u307e\u308b\u65e5\u4ed8\u64cd\u4f5c\u306e\u57fa\u790e<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">JavaScript\u3067\u65e5\u4ed8\u30fb\u6642\u523b\u3092\u6271\u3046\u306b\u306f<code>Date<\/code>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f7f\u3044\u307e\u3059\u3002\u307e\u305a\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3068\u4e3b\u8981\u306a\u30e1\u30bd\u30c3\u30c9\u3092\u6574\u7406\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<div style=\"background:#1e1e1e;border-radius:8px;padding:20px 24px;margin:24px 0;overflow-x:auto;\">\n  <p style=\"margin:0 0 8px;font-size:11px;color:#888;text-transform:uppercase;letter-spacing:1px;\">javascript<\/p>\n  <pre style=\"margin:0;font-family:'Consolas','Monaco',monospace;font-size:14px;line-height:1.6;color:#d4d4d4;white-space:pre;\"><code>\/\/ \u73fe\u5728\u65e5\u6642\u3092\u53d6\u5f97\nconst now = new Date();\nconsole.log(now); \/\/ Wed Jul 17 2026 10:30:00 GMT+0900 (JST)\n\n\/\/ \u7279\u5b9a\u306e\u65e5\u6642\u3092\u6307\u5b9a\u3057\u3066\u751f\u6210\nconst specific = new Date(2026, 6, 17); \/\/ 2026\u5e747\u670817\u65e5\uff08\u6708\u306f0\u59cb\u307e\u308a\uff01\uff09\nconst fromString = new Date('2026-07-17'); \/\/ ISO\u5f62\u5f0f\u306e\u6587\u5b57\u5217\u304b\u3089\nconst fromTimestamp = new Date(1752710400000); \/\/ \u30df\u30ea\u79d2\u30bf\u30a4\u30e0\u30b9\u30bf\u30f3\u30d7\u304b\u3089\n\n\/\/ \u5e74\u30fb\u6708\u30fb\u65e5\u30fb\u6642\u523b\u3092\u500b\u5225\u306b\u53d6\u5f97\nconst year = now.getFullYear();    \/\/ 2026\nconst month = now.getMonth() + 1;  \/\/ 7\uff080\u59cb\u307e\u308a\u306a\u306e\u3067+1\u304c\u5fc5\u8981\uff01\uff09\nconst day = now.getDate();          \/\/ 17\nconst hour = now.getHours();        \/\/ 10\nconst minute = now.getMinutes();    \/\/ 30\nconst second = now.getSeconds();    \/\/ 0<\/code><\/pre>\n<\/div>\n\n\n\n<table>\n<thead><tr><th>\u30e1\u30bd\u30c3\u30c9<\/th><th>\u623b\u308a\u5024\u306e\u4f8b<\/th><th>\u6ce8\u610f\u70b9<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>getFullYear()<\/td><td>2026<\/td><td>getYear()\u306f\u975e\u63a8\u5968\u3002\u5fc5\u305agetFullYear()\u3092\u4f7f\u3046<\/td><\/tr>\n<tr><td>getMonth()<\/td><td>6\uff087\u6708\u306e\u5834\u5408\uff09<\/td><td>0\u301c11\u306e\u5024\u3002\u8868\u793a\u6642\u306f\u5fc5\u305a+1\u3059\u308b<\/td><\/tr>\n<tr><td>getDate()<\/td><td>17<\/td><td>\u300c\u65e5\u300d\u3092\u8fd4\u3059\u3002getDay()\u3068\u306f\u5225\u7269\uff08getDay()\u306f\u66dc\u65e5\uff09<\/td><\/tr>\n<tr><td>getDay()<\/td><td>4\uff08\u6728\u66dc\u65e5\uff09<\/td><td>0=\u65e5\u66dc\u301c6=\u571f\u66dc\u3002\u66dc\u65e5\u3092\u6570\u5024\u3067\u8fd4\u3059<\/td><\/tr>\n<tr><td>getHours()<\/td><td>10<\/td><td>0\u301c23\u306e24\u6642\u9593\u8868\u8a18<\/td><\/tr>\n<tr><td>getTime()<\/td><td>1752710400000<\/td><td>Unix\u6642\u523b\uff081970\/1\/1\u304b\u3089\u306e\u30df\u30ea\u79d2\uff09\u3002\u65e5\u4ed8\u6bd4\u8f03\u306b\u4f7f\u3046<\/td><\/tr>\n<tr><td>toISOString()<\/td><td>2026-07-17T01:30:00.000Z<\/td><td>UTC\u57fa\u6e96\u306eISO 8601\u5f62\u5f0f\u3002API\u306b\u6e21\u3059\u969b\u306b\u4fbf\u5229<\/td><\/tr>\n<tr><td>toLocaleDateString()<\/td><td>2026\/7\/17\uff08\u65e5\u672c\u74b0\u5883\u306e\u5834\u5408\uff09<\/td><td>\u30ed\u30b1\u30fc\u30eb\u4f9d\u5b58\u3002\u74b0\u5883\u306b\u3088\u3063\u3066\u8868\u793a\u304c\u5909\u308f\u308b<\/td><\/tr>\n<\/tbody>\n<\/table>\n\n\n\n<div style=\"background:#f8f9fa;border-left:4px solid #6b7280;border-radius:0 8px 8px 0;padding:16px 20px;margin:20px 0;\">\n  <p style=\"margin:0 0 4px;font-size:13px;font-weight:700;color:#6b7280;letter-spacing:1px;\">&#128218; \u7528\u8a9e\u89e3\u8aac<\/p>\n  <p style=\"margin:0;font-size:15px;line-height:1.7;\"><strong>Unix\u6642\u523b\uff08Unix\u30bf\u30a4\u30e0\u30b9\u30bf\u30f3\u30d7\uff09<\/strong>\uff1a1970\u5e741\u67081\u65e500:00:00 UTC\uff08Coordinated Universal Time\uff09\u304b\u3089\u306e\u7d4c\u904e\u30df\u30ea\u79d2\u6570\u3002Date.getTime()\u304c\u8fd4\u3059\u5024\u304c\u3053\u308c\u306b\u3042\u305f\u308b\u3002\u300c2026-07-17T00:00:00Z\u300d\u306f\u6570\u5024\u3067\u8a00\u3046\u3068\u7d041752710400000\u30df\u30ea\u79d2\u3002\u6570\u5024\u306a\u306e\u3067\u5927\u5c0f\u6bd4\u8f03\uff08>\u30fb<\u30fb===\uff09\u304c\u6b63\u78ba\u306b\u6a5f\u80fd\u3059\u308b\u305f\u3081\u3001\u65e5\u4ed8\u6bd4\u8f03\u306b\u306f\u3053\u306e\u5024\u3092\u4f7f\u3046\u306e\u304c\u6700\u3082\u5b89\u5168\u3002<\/p>\n<\/div>\n\n\n\n<div style=\"background:#fef2f2;border:2px solid #dc2626;border-radius:8px;padding:20px 24px;margin:24px 0;\">\n  <div style=\"display:flex;align-items:center;gap:8px;margin-bottom:12px;\">\n    <span style=\"font-size:20px;\">&#9888;&#65039;<\/span>\n    <strong style=\"color:#dc2626;font-size:16px;\">getMonth()\u306f0\u59cb\u307e\u308a\uff1a\u6700\u3082\u3088\u304f\u3042\u308b\u521d\u5fc3\u8005\u30d0\u30b0<\/strong>\n  <\/div>\n  <p style=\"margin:0;font-size:15px;line-height:1.8;color:#333;\">JavaScript\u306egetMonth()\u306f\u300c0=1\u6708\u30016=7\u6708\u300111=12\u6708\u300d\u3092\u8fd4\u3057\u307e\u3059\u3002\u300c7\u670817\u65e5\u300d\u306e\u6708\u3092\u53d6\u5f97\u3057\u305f\u3044\u5834\u5408\u3001getMonth()\u306e\u623b\u308a\u5024\u306f\u300c7\u300d\u3067\u306f\u306a\u304f\u300c6\u300d\u3067\u3059\u3002\u8868\u793a\u3059\u308b\u969b\u306f\u5fc5\u305a+1\u3057\u3066\u304f\u3060\u3055\u3044\u3002\u306a\u304a\u3001new Date(\u5e74, \u6708, \u65e5)\u3067Date\u3092\u751f\u6210\u3059\u308b\u6642\u3082\u6708\u306f0\u59cb\u307e\u308a\u3067\u3059\u3002\u300cnew Date(2026, 7, 17)\u300d\u306f\u300c7\u670817\u65e5\u300d\u3067\u306f\u306a\u304f\u300c8\u670817\u65e5\u300d\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-javascript-date-compare-3&#038;blog_slug=cc-javascript-date-compare-3\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-javascript-date-compare-3&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-02\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">02<\/span>\n  <span class=\"section-label\" style=\"display:block;\">DATE COMPARISON<\/span>\n  <span class=\"section-title\" style=\"display:block;\">\u65e5\u4ed8\u306e\u6bd4\u8f03\u65b9\u6cd5\uff1agetTime()\u30fb\u6bd4\u8f03\u6f14\u7b97\u5b50\u306e\u4f7f\u3044\u65b9<\/span>\n  <span class=\"section-desc\">\u300c\u6587\u5b57\u5217\u6bd4\u8f03\u300dvs\u300c\u30df\u30ea\u79d2\u6bd4\u8f03\u300d\u306e\u4f7f\u3044\u5206\u3051<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">JavaScript\u3067\u306e\u65e5\u4ed8\u6bd4\u8f03\u306b\u306f\u3044\u304f\u3064\u304b\u306e\u65b9\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002\u305d\u308c\u305e\u308c\u306e\u52d5\u4f5c\u3068\u4f7f\u3044\u5206\u3051\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<div style=\"background:#1e1e1e;border-radius:8px;padding:20px 24px;margin:24px 0;overflow-x:auto;\">\n  <p style=\"margin:0 0 8px;font-size:11px;color:#888;text-transform:uppercase;letter-spacing:1px;\">javascript<\/p>\n  <pre style=\"margin:0;font-family:'Consolas','Monaco',monospace;font-size:14px;line-height:1.6;color:#d4d4d4;white-space:pre;\"><code>const date1 = new Date('2026-03-01');\nconst date2 = new Date('2026-11-15');\n\n\/\/ \u65b9\u6cd51: \u6bd4\u8f03\u6f14\u7b97\u5b50\uff08&lt; &gt; \u306f\u4f7f\u3048\u308b\uff09\nconsole.log(date1 &lt; date2);  \/\/ true\uff08date1\u304c\u904e\u53bb\uff09\nconsole.log(date1 &gt; date2);  \/\/ false\n\n\/\/ \u65b9\u6cd52: getTime()\u3067ms\u5909\u63db\u3057\u3066\u304b\u3089\u6bd4\u8f03\uff08\u6700\u3082\u78ba\u5b9f\uff09\nconsole.log(date1.getTime() &lt; date2.getTime());  \/\/ true\nconsole.log(date1.getTime() === date2.getTime()); \/\/ false\n\n\/\/ \u6ce8\u610f: == \u3084 === \u306f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u53c2\u7167\u6bd4\u8f03\u306b\u306a\u308b\u305f\u3081\u4f7f\u3048\u306a\u3044\nconst d1 = new Date('2026-07-17');\nconst d2 = new Date('2026-07-17');\nconsole.log(d1 == d2);  \/\/ false\uff08\u540c\u3058\u65e5\u4ed8\u3067\u3082\u5225\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\uff09\nconsole.log(d1.getTime() === d2.getTime()); \/\/ true\uff08\u6b63\u3057\u3044\u6bd4\u8f03\uff09<\/code><\/pre>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">\u91cd\u8981\u306a\u6ce8\u610f\u70b9\uff1a<strong>Date\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u540c\u58eb\u3092\u300c==\u300d\u3084\u300c===\u300d\u3067\u6bd4\u8f03\u3057\u3066\u306f\u3044\u3051\u307e\u305b\u3093\u3002<\/strong>\u540c\u3058\u65e5\u4ed8\u3092\u8868\u3059Date\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3067\u3082\u3001\u7570\u306a\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u3057\u3066\u751f\u6210\u3055\u308c\u305f\u5834\u5408\u306f\u300c==\u300d\u3067\u6bd4\u8f03\u3059\u308b\u3068\u5fc5\u305afalse\u306b\u306a\u308a\u307e\u3059\u3002\u65e5\u4ed8\u306e\u7b49\u4fa1\u6bd4\u8f03\u306f\u5fc5\u305a<code>getTime()<\/code>\u3092\u4f7f\u3063\u3066\u6570\u5024\uff08\u30df\u30ea\u79d2\uff09\u306b\u5909\u63db\u3057\u3066\u304b\u3089\u6bd4\u8f03\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<div style=\"background:#f8f9fa;border-left:4px solid #6b7280;border-radius:0 8px 8px 0;padding:16px 20px;margin:20px 0;\">\n  <p style=\"margin:0 0 4px;font-size:13px;font-weight:700;color:#6b7280;letter-spacing:1px;\">&#128218; \u7528\u8a9e\u89e3\u8aac<\/p>\n  <p style=\"margin:0;font-size:15px;line-height:1.7;\"><strong>\u53c2\u7167\u6bd4\u8f03 vs \u5024\u6bd4\u8f03<\/strong>\uff1aJavaScript\u3067\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\uff08Date\u30fbArray\u30fbObject\u7b49\uff09\u3092==\u3084===\u3067\u6bd4\u8f03\u3059\u308b\u3068\u3001\u300c\u540c\u3058\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u6307\u3057\u3066\u3044\u308b\u304b\uff08\u53c2\u7167\u6bd4\u8f03\uff09\u300d\u304c\u884c\u308f\u308c\u308b\u3002\u300c\u540c\u3058\u5185\u5bb9\u304b\uff08\u5024\u6bd4\u8f03\uff09\u300d\u3067\u306f\u306a\u3044\u3002\u305d\u306e\u305f\u3081\u540c\u3058\u65e5\u4ed8\u3092\u8868\u30592\u3064\u306eDate\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092==\u3067\u6bd4\u8f03\u3059\u308b\u3068false\u306b\u306a\u308b\u3002\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\uff08\u6570\u5024\u30fb\u6587\u5b57\u5217\u30fb\u771f\u507d\u5024\uff09\u306f\u5024\u6bd4\u8f03\u304c\u884c\u308f\u308c\u308b\u305f\u3081\u3001getTime()\u3067\u6570\u5024\u306b\u5909\u63db\u3057\u3066\u304b\u3089===\u6bd4\u8f03\u3059\u308b\u3053\u3068\u3067\u6b63\u78ba\u306a\u65e5\u4ed8\u306e\u7b49\u4fa1\u5224\u5b9a\u304c\u3067\u304d\u308b\u3002<\/p>\n<\/div>\n\n\n\n<table>\n<thead><tr><th>\u6bd4\u8f03\u65b9\u6cd5<\/th><th>\u30b3\u30fc\u30c9\u4f8b<\/th><th>\u4f7f\u3048\u308b\u304b<\/th><th>\u8aac\u660e<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>< > \u3067\u5927\u5c0f\u6bd4\u8f03<\/td><td>date1 < date2<\/td><td>OK<\/td><td>\u65e5\u4ed8\u306e\u524d\u5f8c\u95a2\u4fc2\u306e\u6bd4\u8f03\u306b\u4f7f\u3048\u308b<\/td><\/tr>\n<tr><td>== \u3067\u7b49\u4fa1\u6bd4\u8f03<\/td><td>date1 == date2<\/td><td>NG<\/td><td>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u53c2\u7167\u6bd4\u8f03\u306e\u305f\u3081\u540c\u3058\u65e5\u4ed8\u3067\u3082false<\/td><\/tr>\n<tr><td>=== \u3067\u53b3\u5bc6\u7b49\u4fa1<\/td><td>date1 === date2<\/td><td>NG<\/td><td>== \u3068\u540c\u3058\u554f\u984c\u3067\u4f7f\u3048\u306a\u3044<\/td><\/tr>\n<tr><td>getTime()\u5909\u63db\u5f8c ===<\/td><td>date1.getTime() === date2.getTime()<\/td><td>OK<\/td><td>\u6700\u3082\u78ba\u5b9f\u3002\u6570\u5024\u6bd4\u8f03\u306b\u306a\u308b\u305f\u3081\u6b63\u78ba<\/td><\/tr>\n<tr><td>valueOf()\u5909\u63db\u5f8c ===<\/td><td>date1.valueOf() === date2.valueOf()<\/td><td>OK<\/td><td>getTime()\u3068\u540c\u7b49\uff08valueOf()\u306fgetTime()\u3092\u547c\u3076\uff09<\/td><\/tr>\n<tr><td>\u6587\u5b57\u5217\u5909\u63db\u5f8c ===<\/td><td>date1.toISOString() === date2.toISOString()<\/td><td>\u6761\u4ef6\u4ed8\u304dOK<\/td><td>\u4e21\u8005\u304c\u540c\u3058UTC\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u306a\u3089\u4f7f\u3048\u308b\u304c\u4e0d\u5b89\u5b9a<\/td><\/tr>\n<\/tbody>\n<\/table>\n\n\n\n<div class=\"balloon-wrap\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/ceo-sugasawa.jpg\" alt=\"\u4ee3\u8868\u83c5\u6fa4\">\n    <span class=\"balloon-name\">\u4ee3\u8868\u83c5\u6fa4<\/span>\n  <\/div>\n  <div class=\"balloon-body\">\u300c\u6587\u5b57\u5217\u3067\u6bd4\u8f03\u3059\u308c\u3070\u826f\u3044\u306e\u3067\u306f\uff1f\u300d\u3068\u3044\u3046\u8003\u3048\u65b9\u3082\u3042\u308a\u307e\u3059\u3002ISO\u5f62\u5f0f\uff08YYYY-MM-DD\uff09\u306a\u3089\u30a2\u30eb\u30d5\u30a1\u30d9\u30c3\u30c8\u9806=\u65e5\u4ed8\u9806\u306b\u306a\u308b\u305f\u3081\u3001\u6587\u5b57\u5217\u6bd4\u8f03\u3067\u3082\u5927\u5c0f\u95a2\u4fc2\u306f\u5224\u5b9a\u3067\u304d\u307e\u3059\u3002\u305f\u3060\u3057\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u306e\u9055\u3044\u3067\u610f\u56f3\u3057\u306a\u3044\u7d50\u679c\u306b\u306a\u308b\u30b1\u30fc\u30b9\u304c\u3042\u308b\u305f\u3081\u3001\u516c\u5f0f\u306a\u51e6\u7406\u3067\u306f\u5fc5\u305agetTime()\u3067\u306e\u6570\u5024\u6bd4\u8f03\u3092\u63a8\u5968\u3057\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-javascript-date-compare-3&#038;blog_slug=cc-javascript-date-compare-3\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-javascript-date-compare-3&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-03\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">03<\/span>\n  <span class=\"section-label\" style=\"display:block;\">DATE DIFF<\/span>\n  <span class=\"section-title\" style=\"display:block;\">\u65e5\u4ed8\u5dee\u306e\u8a08\u7b97\uff1a\u65e5\u6570\u30fb\u6642\u9593\u30fb\u5206\u306e\u30df\u30ea\u79d2\u8a08\u7b97<\/span>\n  <span class=\"section-desc\">2\u3064\u306e\u65e5\u4ed8\u306e\u5dee\u3092\u300c\u65e5\u6570\u300d\u300c\u6642\u9593\u300d\u300c\u5206\u300d\u306b\u5909\u63db\u3059\u308b\u8a08\u7b97\u5f0f<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">2\u3064\u306e\u65e5\u4ed8\u306e\u5dee\uff08\u65e5\u6570\u30fb\u6642\u9593\u30fb\u5206\uff09\u3092\u8a08\u7b97\u3059\u308b\u306b\u306f\u3001\u4e21\u8005\u3092getTime()\u3067\u30df\u30ea\u79d2\u306b\u5909\u63db\u3057\u3066\u304b\u3089\u5f15\u304d\u7b97\u3057\u3001\u5fc5\u8981\u306a\u5358\u4f4d\uff08\u65e5\u30fb\u6642\u9593\u30fb\u5206\uff09\u306b\u63db\u7b97\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<div style=\"background:#1e1e1e;border-radius:8px;padding:20px 24px;margin:24px 0;overflow-x:auto;\">\n  <p style=\"margin:0 0 8px;font-size:11px;color:#888;text-transform:uppercase;letter-spacing:1px;\">javascript<\/p>\n  <pre style=\"margin:0;font-family:'Consolas','Monaco',monospace;font-size:14px;line-height:1.6;color:#d4d4d4;white-space:pre;\"><code>const date1 = new Date('2026-01-01');\nconst date2 = new Date('2026-07-17');\n\n\/\/ \u30df\u30ea\u79d2\u306e\u5dee\u3092\u8a08\u7b97\nconst diffMs = date2.getTime() - date1.getTime();\n\/\/ diffMs = 197 * 24 * 60 * 60 * 1000 = 17020800000\n\n\/\/ \u65e5\u6570\u306b\u5909\u63db\nconst diffDays = Math.floor(diffMs \/ (1000 * 60 * 60 * 24));\nconsole.log(diffDays); \/\/ 197\uff08\u65e5\uff09\n\n\/\/ \u6642\u9593\u306b\u5909\u63db\nconst diffHours = Math.floor(diffMs \/ (1000 * 60 * 60));\nconsole.log(diffHours); \/\/ 4728\uff08\u6642\u9593\uff09\n\n\/\/ \u5206\u306b\u5909\u63db\nconst diffMinutes = Math.floor(diffMs \/ (1000 * 60));\nconsole.log(diffMinutes); \/\/ 283680\uff08\u5206\uff09\n\n\/\/ \u300c\u4f55\u65e5\u4f55\u6642\u9593\u4f55\u5206\u300d\u306e\u8868\u793a\nconst days = Math.floor(diffMs \/ (1000 * 60 * 60 * 24));\nconst hours = Math.floor((diffMs % (1000 * 60 * 60 * 24)) \/ (1000 * 60 * 60));\nconst minutes = Math.floor((diffMs % (1000 * 60 * 60)) \/ (1000 * 60));\nconsole.log(`${days}\u65e5${hours}\u6642\u9593${minutes}\u5206`); \/\/ 197\u65e50\u6642\u95930\u5206<\/code><\/pre>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">\u30df\u30ea\u79d2\u63db\u7b97\u306e\u899a\u3048\u65b9\uff1a<strong>1\u79d2=1,000ms \u2192 1\u5206=60,000ms \u2192 1\u6642\u9593=3,600,000ms \u2192 1\u65e5=86,400,000ms<\/strong>\u3002\u65e5\u4ed8\u5dee\u3092\u65e5\u6570\u306b\u5909\u63db\u3059\u308b\u969b\u306f\u300cdiffMs \u00f7 86,400,000\u300d\u3067\u8a08\u7b97\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<div style=\"background:#fef2f2;border:2px solid #dc2626;border-radius:8px;padding:20px 24px;margin:24px 0;\">\n  <div style=\"display:flex;align-items:center;gap:8px;margin-bottom:12px;\">\n    <span style=\"font-size:20px;\">&#9888;&#65039;<\/span>\n    <strong style=\"color:#dc2626;font-size:16px;\">\u590f\u6642\u9593\uff08\u30b5\u30de\u30fc\u30bf\u30a4\u30e0\uff09\u306e\u3042\u308b\u56fd\u306e\u65e5\u4ed8\u8a08\u7b97\u306b\u6ce8\u610f<\/strong>\n  <\/div>\n  <p style=\"margin:0;font-size:15px;line-height:1.8;color:#333;\">\u65e5\u672c\uff08JST\uff09\u306f\u590f\u6642\u9593\u304c\u306a\u3044\u305f\u3081\u3053\u306e\u554f\u984c\u306f\u5c11\u306a\u3044\u3067\u3059\u304c\u3001\u30a2\u30e1\u30ea\u30ab\u30fb\u30e8\u30fc\u30ed\u30c3\u30d1\u306a\u3069\u306e\u30b5\u30de\u30fc\u30bf\u30a4\u30e0\u304c\u3042\u308b\u5730\u57df\u3067\u306f1\u65e5\u306e\u9577\u3055\u304c23\u6642\u9593\u307e\u305f\u306f25\u6642\u9593\u306b\u306a\u308b\u65e5\u304c\u3042\u308a\u307e\u3059\u3002Date\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306f\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u3092\u8003\u616e\u3057\u305f\u5b9f\u969b\u306e\u6642\u523b\u3092\u6271\u3046\u305f\u3081\u3001\u30b5\u30de\u30fc\u30bf\u30a4\u30e0\u3092\u307e\u305f\u3050\u65e5\u4ed8\u5dee\u306e\u8a08\u7b97\u3067\u306f\u8aa4\u5dee\u304c\u751f\u3058\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002\u30b0\u30ed\u30fc\u30d0\u30eb\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306fdayjs\u3084date-fns\u306a\u3069\u306e\u30e9\u30a4\u30d6\u30e9\u30ea\u306e\u4f7f\u7528\u3092\u691c\u8a0e\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<\/div>\n\n\n\n<div style=\"background:#f8f9fa;border-left:4px solid #6b7280;border-radius:0 8px 8px 0;padding:16px 20px;margin:20px 0;\">\n  <p style=\"margin:0 0 4px;font-size:13px;font-weight:700;color:#6b7280;letter-spacing:1px;\">&#128218; \u7528\u8a9e\u89e3\u8aac<\/p>\n  <p style=\"margin:0;font-size:15px;line-height:1.7;\"><strong>\u30df\u30ea\u79d2\uff08Millisecond\uff09<\/strong>\uff1a1\u79d2\u306e1,000\u5206\u306e1\u3002\u30b3\u30f3\u30d4\u30e5\u30fc\u30bf\u306e\u6642\u523b\u8a08\u7b97\u3067\u306f\u300c1970\u5e741\u67081\u65e50\u66420\u52060\u79d2\uff08UTC\uff09\u304b\u3089\u306e\u30df\u30ea\u79d2\u6570\u300d\uff08Unix\u30bf\u30a4\u30e0\u30b9\u30bf\u30f3\u30d7\uff09\u304c\u6a19\u6e96\u7684\u306b\u4f7f\u308f\u308c\u308b\u3002JavaScript\u306eDate.getTime()\u3082\u30df\u30ea\u79d2\u3092\u8fd4\u3059\u3002\u30df\u30ea\u79d2\u3067\u6271\u3046\u3053\u3068\u3067\u3001\u65e5\u4ed8\u30fb\u6642\u523b\u3092\u6574\u6570\uff08Int64\uff09\u3068\u3057\u3066\u7cbe\u78ba\u306b\u6bd4\u8f03\u30fb\u8a08\u7b97\u3067\u304d\u308b\u3002<\/p>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-javascript-date-compare-3&#038;blog_slug=cc-javascript-date-compare-3\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-javascript-date-compare-3&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-04\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">04<\/span>\n  <span class=\"section-label\" style=\"display:block;\">DATE FORMAT<\/span>\n  <span class=\"section-title\" style=\"display:block;\">\u65e5\u4ed8\u306e\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\uff1aYYYY-MM-DD\u30fb\u65e5\u672c\u8a9e\u5f62\u5f0f\u306b\u5909\u63db<\/span>\n  <span class=\"section-desc\">\u6a19\u6e96\u30e1\u30bd\u30c3\u30c9\u3067\u5bfe\u5fdc\u3067\u304d\u306a\u3044\u66f8\u5f0f\u5909\u63db\u306e\u5b9f\u88c5\u65b9\u6cd5<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">JavaScript\u306b\u306fPHP\u306edate()\u95a2\u6570\u306e\u3088\u3046\u306a\u6c4e\u7528\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u95a2\u6570\u304c\u6a19\u6e96\u88c5\u5099\u3055\u308c\u3066\u3044\u307e\u305b\u3093\u3002\u300cYYYY-MM-DD\u300d\u300cYYYY\u5e74MM\u6708DD\u65e5\u300d\u306a\u3069\u306e\u5f62\u5f0f\u306b\u5909\u63db\u3059\u308b\u306b\u306f\u3001getFullYear()\u30fbgetMonth()\u30fbgetDate()\u3092\u7d44\u307f\u5408\u308f\u305b\u3066\u81ea\u524d\u3067\u5b9f\u88c5\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<div style=\"background:#1e1e1e;border-radius:8px;padding:20px 24px;margin:24px 0;overflow-x:auto;\">\n  <p style=\"margin:0 0 8px;font-size:11px;color:#888;text-transform:uppercase;letter-spacing:1px;\">javascript<\/p>\n  <pre style=\"margin:0;font-family:'Consolas','Monaco',monospace;font-size:14px;line-height:1.6;color:#d4d4d4;white-space:pre;\"><code>const now = new Date();\n\n\/\/ YYYY-MM-DD\u5f62\u5f0f\uff08\u30bc\u30ed\u57cb\u3081\u4ed8\u304d\uff09\nfunction formatDate(date) {\n  const y = date.getFullYear();\n  const m = String(date.getMonth() + 1).padStart(2, '0'); \/\/ 2\u6841\u30bc\u30ed\u57cb\u3081\n  const d = String(date.getDate()).padStart(2, '0');\n  return `${y}-${m}-${d}`;\n}\nconsole.log(formatDate(now)); \/\/ 2026-07-17\n\n\/\/ \u65e5\u672c\u8a9e\u5f62\u5f0f\nfunction formatDateJP(date) {\n  return `${date.getFullYear()}\u5e74${date.getMonth() + 1}\u6708${date.getDate()}\u65e5`;\n}\nconsole.log(formatDateJP(now)); \/\/ 2026\u5e747\u670817\u65e5\n\n\/\/ ISO 8601\u5f62\u5f0f\uff08UTC\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\uff09\nconsole.log(now.toISOString()); \/\/ 2026-07-17T01:30:00.000Z\n\n\/\/ Intl.DateTimeFormat\uff08\u30ed\u30b1\u30fc\u30eb\u5bfe\u5fdc\uff09\nconst jpFormatter = new Intl.DateTimeFormat('ja-JP', {\n  year: 'numeric', month: 'long', day: 'numeric', weekday: 'long'\n});\nconsole.log(jpFormatter.format(now)); \/\/ 2026\u5e747\u670817\u65e5\u6728\u66dc\u65e5<\/code><\/pre>\n<\/div>\n\n\n\n<div style=\"background:#f0fdf4;border:1px solid #22c55e;border-radius:8px;padding:20px 24px;margin:24px 0;\">\n  <div style=\"display:flex;align-items:center;gap:8px;margin-bottom:12px;\">\n    <span style=\"font-size:18px;\">&#128161;<\/span>\n    <strong style=\"color:#16a34a;font-size:15px;\">padStart(2, \"0\")\u3067\u30bc\u30ed\u57cb\u3081<\/strong>\n  <\/div>\n  <p style=\"margin:0;font-size:15px;line-height:1.8;color:#333;\">\u300c07\u300d\u300c03\u300d\u306e\u3088\u3046\u306b2\u6841\u56fa\u5b9a\u3067\u8868\u793a\u3057\u305f\u3044\u5834\u5408\u3001String(value).padStart(2, \"0\") \u304c\u4fbf\u5229\u3067\u3059\u3002\u300cgetMonth() + 1\u300d\u306e\u7d50\u679c\u304c1\u6841\u306e\u5834\u5408\u30822\u6841\u306b\u305d\u308d\u3048\u3066\u304f\u308c\u307e\u3059\u3002\u4f8b: String(7).padStart(2, \"0\") \u2192 \"07\"\u3002<\/p>\n<\/div>\n\n\n\n<h3 class=\"wp-block-heading\">\u65e5\u4ed8\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u306e\u30e9\u30a4\u30d6\u30e9\u30ea\u6bd4\u8f03\uff1a\u6a19\u6e96 vs day.js vs date-fns<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u65e5\u4ed8\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u304c\u8907\u96d1\u306b\u306a\u308b\u5834\u5408\u306f\u30e9\u30a4\u30d6\u30e9\u30ea\u3092\u4f7f\u3046\u306e\u304c\u73fe\u5b9f\u7684\u3067\u3059\u3002\u4e3b\u8981\u306a\u9078\u629e\u80a2\u3092\u6bd4\u8f03\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<table>\n<thead><tr><th>\u9078\u629e\u80a2<\/th><th>\u30d0\u30f3\u30c9\u30eb\u30b5\u30a4\u30ba<\/th><th>\u66f8\u304d\u65b9\u306e\u4f8b<\/th><th>\u5411\u3044\u3066\u3044\u308b\u30b1\u30fc\u30b9<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>\u6a19\u6e96Date API<\/td><td>0KB\uff08\u7d44\u307f\u8fbc\u307f\uff09<\/td><td>padStart\u7b49\u3067\u81ea\u524d\u5b9f\u88c5<\/td><td>\u7c21\u5358\u306a\u8868\u793a\u30fb\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u304c\u8efd\u91cf\u91cd\u8996<\/td><\/tr>\n<tr><td>day.js<\/td><td>\u7d042KB<\/td><td>dayjs().format(\"YYYY-MM-DD\")<\/td><td>\u6700\u3082\u4eba\u6c17\u3002Moment.js\u304b\u3089\u306e\u4e57\u308a\u63db\u3048\u304c\u591a\u3044<\/td><\/tr>\n<tr><td>date-fns<\/td><td>\u5fc5\u8981\u306a\u95a2\u6570\u3060\u3051\uff08\u30c4\u30ea\u30fc\u30b7\u30a7\u30a4\u30af\u5bfe\u5fdc\uff09<\/td><td>format(date, \"yyyy-MM-dd\")<\/td><td>\u95a2\u6570\u578b\u30b9\u30bf\u30a4\u30eb\u30fbTypeScript\u5bfe\u5fdc\u304c\u91cd\u8981\u306a\u5834\u5408<\/td><\/tr>\n<tr><td>Temporal API\uff08\u5c06\u6765\uff09<\/td><td>\u7d44\u307f\u8fbc\u307f\uff08\u63d0\u6848\u4e2d\uff09<\/td><td>Temporal.PlainDate.from(\"2026-07-17\")<\/td><td>\u30d6\u30e9\u30a6\u30b6\u6a19\u6e96\u5316\u5f8c\u306e\u6b21\u4e16\u4ee3\u6a19\u6e96\uff08\u73fe\u6642\u70b9\u306fpolyfill\u5fc5\u8981\uff09<\/td><\/tr>\n<\/tbody>\n<\/table>\n\n\n\n<p class=\"wp-block-paragraph\">\u5c0f\u898f\u6a21\u306a\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3084\u300c\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u304c\u6570\u30d1\u30bf\u30fc\u30f3\u3057\u304b\u306a\u3044\u300d\u5834\u5408\u306f\u6a19\u6e96DateAPI\u3067\u5341\u5206\u3067\u3059\u3002\u305f\u3060\u3057<strong>\u65e5\u4ed8\u64cd\u4f5c\u304c\u983b\u7e41\u306b\u5fc5\u8981\u30fb\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u64cd\u4f5c\u304c\u5fc5\u8981\u30fb\u30c1\u30fc\u30e0\u3067\u4e00\u8cab\u3057\u305fAPI\u3092\u4f7f\u3044\u305f\u3044<\/strong>\u5834\u5408\u306fday.js\u306e\u5c0e\u5165\u3092\u5f37\u304f\u304a\u52e7\u3081\u3057\u307e\u3059\u3002<\/p><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u73fe\u4ee3\u306e\u30d6\u30e9\u30a6\u30b6\u30fbNode.js\u3067\u306f<code>Intl.DateTimeFormat<\/code>\u306b\u3088\u308b\u56fd\u969b\u5316\u5bfe\u5fdc\u306e\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u3082\u5229\u7528\u3067\u304d\u307e\u3059\u3002\u305f\u3060\u3057\u3001\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u65e5\u4ed8\u64cd\u4f5c\u304c\u983b\u7e41\u306b\u5fc5\u8981\u306a\u5834\u5408\u306f<strong>day.js\uff08\u8efd\u91cf\u30fb\u4eba\u6c17\uff09\u3084date-fns\uff08\u95a2\u6570\u578b\u30fb\u30c4\u30ea\u30fc\u30b7\u30a7\u30a4\u30af\u5bfe\u5fdc\uff09\u306a\u3069\u306e\u30e9\u30a4\u30d6\u30e9\u30ea\u306e\u5c0e\u5165<\/strong>\u3082\u691c\u8a0e\u3057\u3066\u304f\u3060\u3055\u3044\u3002\u6a19\u6e96API\u3088\u308a\u7c21\u6f54\u306a\u30b3\u30fc\u30c9\u3067\u8907\u96d1\u306a\u65e5\u4ed8\u64cd\u4f5c\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-javascript-date-compare-3&#038;blog_slug=cc-javascript-date-compare-3\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-javascript-date-compare-3&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-05\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">05<\/span>\n  <span class=\"section-label\" style=\"display:block;\">COMMON BUGS<\/span>\n  <span class=\"section-title\" style=\"display:block;\">\u3088\u304f\u3042\u308b\u30d0\u30b0\u3068\u843d\u3068\u3057\u7a74\uff1a\u6708\u306f0\u59cb\u307e\u308a\u30fb\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u554f\u984c<\/span>\n  <span class=\"section-desc\">\u5b9f\u52d9\u3067\u3088\u304f\u906d\u9047\u3059\u308b\u65e5\u4ed8\u30d0\u30b0\u306e\u30d1\u30bf\u30fc\u30f3\u3068\u5bfe\u51e6\u6cd5<\/span>\n<\/h2>\n\n\n\n<table>\n<thead><tr><th>\u30d0\u30b0\u30d1\u30bf\u30fc\u30f3<\/th><th>\u75c7\u72b6<\/th><th>\u539f\u56e0<\/th><th>\u89e3\u6c7a\u7b56<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>\u6708\u304c1\u305a\u308c\u308b<\/td><td>7\u6708\u306e\u3064\u3082\u308a\u304c8\u6708\u3068\u8868\u793a\u3055\u308c\u308b<\/td><td>new Date(2026, 7, 1)\u306e\u6708\u306f0\u59cb\u307e\u308a\u3067\u300c8\u6708\u300d<\/td><td>new Date(2026, 6, 1)\u306b\u4fee\u6b63\uff087\u6708=6\uff09<\/td><\/tr>\n<tr><td>\u65e5\u4ed8\u6bd4\u8f03\u3067true\u306b\u306a\u3089\u306a\u3044<\/td><td>\u540c\u3058\u65e5\u4ed8\u306a\u306e\u306b==\u304cfalse<\/td><td>Date\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306f\u53c2\u7167\u6bd4\u8f03<\/td><td>getTime()===getTime()\u3067\u6bd4\u8f03<\/td><\/tr>\n<tr><td>\u6587\u5b57\u5217\u306e\u65e5\u4ed8\u6bd4\u8f03\u3067\u30d0\u30b0<\/td><td>\"2024-3-1\" > \"2024-11-15\"\u304ctrue\u306b\u306a\u308b<\/td><td>\u30bc\u30ed\u57cb\u3081\u306a\u3057\u306e\u6587\u5b57\u5217\u6bd4\u8f03\u306f\u6587\u5b57\u30b3\u30fc\u30c9\u9806<\/td><td>new Date()\u3067\u30d1\u30fc\u30b9\u3057\u3066getTime()\u6bd4\u8f03<\/td><\/tr>\n<tr><td>UTC vs JST\u6642\u523b\u30ba\u30ec<\/td><td>new Date(\"2026-07-17\")\u304c7\u670816\u65e5\u306b\u306a\u308b<\/td><td>ISO\u6587\u5b57\u5217\u306fUTC\u3068\u3057\u3066\u89e3\u91c8\u3055\u308c\u308b<\/td><td>\"2026-07-17T00:00:00+09:00\"\u3068\u660e\u793a\u3059\u308b<\/td><\/tr>\n<tr><td>\u3046\u308b\u3046\u5e74\u306e\u8a08\u7b97\u30df\u30b9<\/td><td>2\u670829\u65e5\u306e\u7fcc\u65e5\u304c3\u67082\u65e5\u306b\u306a\u308b<\/td><td>\u624b\u52d5\u3067\u65e5\u6570\u8a08\u7b97\u3059\u308b\u3068\u3046\u308b\u3046\u5e74\u3092\u8003\u616e\u3057\u306a\u3044<\/td><td>setDate()\u3092\u4f7f\u3063\u3066\u8a08\u7b97\u3059\u308b<\/td><\/tr>\n<tr><td>midnight\u76f4\u524d\u306e\u65e5\u4ed8\u30ba\u30ec<\/td><td>23:59:59\u306b\u53d6\u5f97\u3057\u305f\u65e5\u4ed8\u304c\u7fcc\u65e5\u306b\u306a\u308b<\/td><td>\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u5909\u63db\u5f8c\u306b\u65e5\u3092\u307e\u305f\u3050<\/td><td>toLocaleDateString()\u304b\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u6307\u5b9a\u3092\u4f7f\u3046<\/td><\/tr>\n<\/tbody>\n<\/table>\n\n\n\n<div style=\"background:#1e1e1e;border-radius:8px;padding:20px 24px;margin:24px 0;overflow-x:auto;\">\n  <p style=\"margin:0 0 8px;font-size:11px;color:#888;text-transform:uppercase;letter-spacing:1px;\">javascript<\/p>\n  <pre style=\"margin:0;font-family:'Consolas','Monaco',monospace;font-size:14px;line-height:1.6;color:#d4d4d4;white-space:pre;\"><code>\/\/ \u30d0\u30b0\u4f8b1: \u6708\u306f0\u59cb\u307e\u308a\u306e\u30df\u30b9\nconst wrong = new Date(2026, 7, 1); \/\/ 8\u67081\u65e5\u306b\u306a\u3063\u3066\u3057\u307e\u3046\uff01\nconst correct = new Date(2026, 6, 1); \/\/ 7\u67081\u65e5\uff08\u6b63\u3057\u3044\uff09\n\n\/\/ \u30d0\u30b0\u4f8b2: ISO\u6587\u5b57\u5217\u306e\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u554f\u984c\nconst d1 = new Date(\"2026-07-17\"); \/\/ UTC\u5348\u524d0\u6642\u3068\u3057\u3066\u89e3\u91c8 \u2192 JST\u3067\u306f\u524d\u65e5\u306e23:00\nconst d2 = new Date(\"2026-07-17T00:00:00+09:00\"); \/\/ JST\u6307\u5b9a\u3067\u6b63\u3057\u3044\n\n\/\/ \u30d0\u30b0\u4f8b3: \u6587\u5b57\u5217\u6bd4\u8f03\u306e\u7f60\n\"2024-3-1\" &gt; \"2024-11-15\" \/\/ true\uff08\u6587\u5b57\u30b3\u30fc\u30c9\u3067\"3\" &gt; \"1\"\u306a\u306e\u3067\u8aa4\u308a\uff09\nnew Date(\"2024-3-1\").getTime() &gt; new Date(\"2024-11-15\").getTime() \/\/ false\uff08\u6b63\u3057\u3044\uff09\n\n\/\/ \u6b63\u3057\u3044\u3046\u308b\u3046\u5e74\u5bfe\u5fdc\u306e\u65e5\u4ed8\u52a0\u7b97\nconst today = new Date();\ntoday.setDate(today.getDate() + 30); \/\/ 30\u65e5\u5f8c\uff08\u3046\u308b\u3046\u5e74\u3082\u81ea\u52d5\u5bfe\u5fdc\uff09<\/code><\/pre>\n<\/div>\n\n\n\n<div class=\"balloon-wrap is-right\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/yamazaki-avatar.png\" alt=\"AI\u9b3c\u7ba1\u7406\u5c71\u5d0e\">\n    <span class=\"balloon-name\">AI\u9b3c\u7ba1\u7406\u5c71\u5d0e<\/span>\n  <\/div>\n  <div class=\"balloon-body\">\u300cISO\u6587\u5b57\u5217\u306e\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u554f\u984c\u300d\u306f\u7279\u306b\u65e5\u672c\u306eWeb\u30a2\u30d7\u30ea\u958b\u767a\u3067\u3088\u304f\u906d\u9047\u3057\u307e\u3059\u3002new Date(\"2026-07-17\")\u306fUTC\u5348\u524d0\u6642\u3068\u3057\u3066\u89e3\u91c8\u3055\u308c\u308b\u305f\u3081\u3001JST\u306b\u5909\u63db\u3059\u308b\u30687\u670816\u65e5\u306e\u5348\u5f8c9\u6642\u306b\u306a\u308a\u307e\u3059\u3002API\u304b\u3089\u53d7\u3051\u53d6\u3063\u305fISO\u6587\u5b57\u5217\u3092\u30ed\u30fc\u30ab\u30eb\u306e\u65e5\u4ed8\u3068\u3057\u3066\u6271\u3046\u969b\u306f\u3001\u5fc5\u305a\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u3092\u610f\u8b58\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/div>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-javascript-date-compare-3&#038;blog_slug=cc-javascript-date-compare-3\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-javascript-date-compare-3&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-06\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">06<\/span>\n  <span class=\"section-label\" style=\"display:block;\">PRACTICAL PATTERNS<\/span>\n  <span class=\"section-title\" style=\"display:block;\">\u5b9f\u7528\u7684\u306aDate\u6d3b\u7528\u30d1\u30bf\u30fc\u30f3\uff1a\u6628\u65e5\u30fb\u660e\u65e5\u30fbN\u65e5\u5f8c\u306e\u8a08\u7b97<\/span>\n  <span class=\"section-desc\">\u3088\u304f\u4f7f\u3046\u65e5\u4ed8\u64cd\u4f5c\u306e\u5b9a\u756a\u30b3\u30fc\u30c9\u3092\u307e\u3068\u3081\u3066\u89e3\u8aac<\/span>\n<\/h2>\n\n\n\n<div style=\"background:#1e1e1e;border-radius:8px;padding:20px 24px;margin:24px 0;overflow-x:auto;\">\n  <p style=\"margin:0 0 8px;font-size:11px;color:#888;text-transform:uppercase;letter-spacing:1px;\">javascript<\/p>\n  <pre style=\"margin:0;font-family:'Consolas','Monaco',monospace;font-size:14px;line-height:1.6;color:#d4d4d4;white-space:pre;\"><code>const today = new Date();\n\n\/\/ \u6628\u65e5\nconst yesterday = new Date(today);\nyesterday.setDate(today.getDate() - 1);\n\n\/\/ \u660e\u65e5\nconst tomorrow = new Date(today);\ntomorrow.setDate(today.getDate() + 1);\n\n\/\/ N\u65e5\u5f8c\nfunction addDays(date, n) {\n  const result = new Date(date);\n  result.setDate(date.getDate() + n);\n  return result;\n}\nconst after30days = addDays(today, 30);\nconst before7days = addDays(today, -7);\n\n\/\/ \u6708\u521d\u30fb\u6708\u672b\nconst firstDayOfMonth = new Date(today.getFullYear(), today.getMonth(), 1);\nconst lastDayOfMonth = new Date(today.getFullYear(), today.getMonth() + 1, 0);\n\/\/ getMonth() + 1\uff08\u7fcc\u6708\uff09\u306e\u300c0\u65e5\u76ee\u300d= \u4eca\u6708\u306e\u672b\u65e5\n\n\/\/ \u4eca\u5e74\u306e\u6b8b\u308a\u65e5\u6570\nconst endOfYear = new Date(today.getFullYear(), 11, 31); \/\/ 12\u670831\u65e5\uff08\u6708\u306f0\u59cb\u307e\u308a\uff09\nconst remainingDays = Math.ceil(\n  (endOfYear.getTime() - today.getTime()) \/ (1000 * 60 * 60 * 24)\n);\n\n\/\/ \u66dc\u65e5\u3092\u65e5\u672c\u8a9e\u3067\u53d6\u5f97\nconst weekdays = [\"\u65e5\", \"\u6708\", \"\u706b\", \"\u6c34\", \"\u6728\", \"\u91d1\", \"\u571f\"];\nconst weekday = weekdays[today.getDay()];\nconsole.log(`\u672c\u65e5\u306f${weekday}\u66dc\u65e5`);<\/code><\/pre>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">\u7279\u306b\u300c\u6708\u672b\u65e5\u306e\u53d6\u5f97\u300d\u306f<strong>new Date(\u5e74, \u7fcc\u6708, 0)\u306eday=0\u30c8\u30ea\u30c3\u30af<\/strong>\u304c\u4fbf\u5229\u3067\u3059\u3002\u300c0\u65e5\u76ee\u300d\u306f\u81ea\u52d5\u7684\u306b\u524d\u6708\u306e\u672b\u65e5\u3092\u6307\u3059\u305f\u3081\u30012\u670828\u65e5\uff08\u3046\u308b\u3046\u5e74\u306a\u308929\u65e5\uff09\u3082\u81ea\u52d5\u3067\u6b63\u3057\u304f\u8fd4\u3055\u308c\u307e\u3059\u3002\u624b\u52d5\u3067\u3046\u308b\u3046\u5e74\u3092\u5224\u5b9a\u3059\u308b\u5fc5\u8981\u304c\u306a\u3044\u305f\u3081\u3001\u3053\u306e\u30d1\u30bf\u30fc\u30f3\u3092\u899a\u3048\u3066\u304a\u304f\u3068\u5b9f\u7528\u7684\u3067\u3059\u3002<\/p>\n\n\n\n<div style=\"background:#f0fdf4;border:1px solid #22c55e;border-radius:8px;padding:20px 24px;margin:24px 0;\">\n  <div style=\"display:flex;align-items:center;gap:8px;margin-bottom:12px;\">\n    <span style=\"font-size:18px;\">&#128161;<\/span>\n    <strong style=\"color:#16a34a;font-size:15px;\">setDate()\u306f\u81ea\u52d5\u7684\u306b\u6708\u3092\u307e\u305f\u3044\u3067\u304f\u308c\u308b<\/strong>\n  <\/div>\n  <p style=\"margin:0;font-size:15px;line-height:1.8;color:#333;\">setDate(today.getDate() + 30)\u306e\u3088\u3046\u306b\u6708\u3092\u307e\u305f\u3050\u65e5\u6570\u3092\u52a0\u7b97\u3057\u3066\u3082\u3001JavaScript\u304c\u81ea\u52d5\u7684\u306b\u7fcc\u6708\u30fb\u7fcc\u5e74\u306e\u6b63\u3057\u3044\u65e5\u4ed8\u306b\u5909\u63db\u3057\u3066\u304f\u308c\u307e\u3059\u3002\u300c1\u670831\u65e5 + 1\u65e5\u300d\u306fsetDate(32)\u306b\u306a\u308a\u307e\u3059\u304c\u3001\u81ea\u52d5\u7684\u306b2\u67081\u65e5\u3068\u3057\u3066\u51e6\u7406\u3055\u308c\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n\n<div style=\"background:#f8f9fa;border-left:4px solid #6b7280;border-radius:0 8px 8px 0;padding:16px 20px;margin:20px 0;\">\n  <p style=\"margin:0 0 4px;font-size:13px;font-weight:700;color:#6b7280;letter-spacing:1px;\">&#128218; \u7528\u8a9e\u89e3\u8aac<\/p>\n  <p style=\"margin:0;font-size:15px;line-height:1.7;\"><strong>\u3046\u308b\u3046\u5e74\uff08\u958f\u5e74 \/ Leap Year\uff09<\/strong>\uff1a2\u6708\u304c29\u65e5\u306b\u306a\u308b\u5e74\u3002\u30b0\u30ec\u30b4\u30ea\u30aa\u66a6\u3067\u306f\u300c4\u3067\u5272\u308a\u5207\u308c\u308b\u5e74\u306f\u3046\u308b\u3046\u5e74\u3002\u305f\u3060\u3057100\u3067\u5272\u308a\u5207\u308c\u308b\u5e74\u306f\u5e73\u5e74\u3002\u305f\u3060\u3057400\u3067\u5272\u308a\u5207\u308c\u308b\u5e74\u306f\u3046\u308b\u3046\u5e74\u300d\u3068\u3044\u3046\u30eb\u30fc\u30eb\u3067\u6c7a\u307e\u308b\u30022024\u5e74\u30fb2028\u5e74\u306f\u3046\u308b\u3046\u5e74\u30012100\u5e74\u30fb2200\u5e74\u30fb2300\u5e74\u306f\u5e73\u5e74\uff08400\u3067\u5272\u308a\u5207\u308c\u306a\u3044\u305f\u3081\uff09\u3002JavaScript\u306esetDate()\u3084new Date(\u5e74, \u6708, \u65e5)\u306f\u3046\u308b\u3046\u5e74\u3092\u81ea\u52d5\u8003\u616e\u3059\u308b\u304c\u3001\u624b\u52d5\u3067\u65e5\u4ed8\u8a08\u7b97\u3059\u308b\u5834\u5408\u306f\u3046\u308b\u3046\u5e74\u5224\u5b9a\u30ed\u30b8\u30c3\u30af\u304c\u5fc5\u8981\u3002<\/p>\n<\/div>\n\n\n\n<div class=\"g-flow-row\" style=\"margin:24px 0;\">\n  <div class=\"g-flow-item\"><strong>\u65e5\u4ed8\u53d6\u5f97<\/strong><br>new Date()<br><span style=\"font-size:12px;\">\u73fe\u5728\u65e5\u6642<\/span><\/div>\n  <div class=\"g-flow-arrow\">&#8594;<\/div>\n  <div class=\"g-flow-item\"><strong>\u8981\u7d20\u62bd\u51fa<\/strong><br>getFullYear()\u7b49<br><span style=\"font-size:12px;\">\u5e74\u6708\u65e5\u6642\u5206\u79d2<\/span><\/div>\n  <div class=\"g-flow-arrow\">&#8594;<\/div>\n  <div class=\"g-flow-item\"><strong>\u6bd4\u8f03\u30fb\u8a08\u7b97<\/strong><br>getTime()\u2192\u6570\u5024<br><span style=\"font-size:12px;\">\u5dee\u30fb\u5927\u5c0f\u6bd4\u8f03<\/span><\/div>\n  <div class=\"g-flow-arrow\">&#8594;<\/div>\n  <div class=\"g-flow-item\"><strong>\u52a0\u6e1b\u7b97<\/strong><br>setDate()<br><span style=\"font-size:12px;\">N\u65e5\u5f8c\u30fb\u524d<\/span><\/div>\n  <div class=\"g-flow-arrow\">&#8594;<\/div>\n  <div class=\"g-flow-item\"><strong>\u30d5\u30a9\u30fc\u30de\u30c3\u30c8<\/strong><br>padStart()\u7b49<br><span style=\"font-size:12px;\">\u8868\u793a\u5f62\u5f0f\u5909\u63db<\/span><\/div>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-javascript-date-compare-3&#038;blog_slug=cc-javascript-date-compare-3\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-javascript-date-compare-3&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-07\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">07<\/span>\n  <span class=\"section-label\" style=\"display:block;\">CLAUDE CODE<\/span>\n  <span class=\"section-title\" style=\"display:block;\">Claude Code\u3067\u65e5\u4ed8\u51e6\u7406\u30d0\u30b0\u3092\u30c7\u30d0\u30c3\u30b0\u3059\u308b\u65b9\u6cd5<\/span>\n  <span class=\"section-desc\">\u65e5\u4ed8\u30d0\u30b0\u306f\u539f\u56e0\u304c\u898b\u3064\u3051\u306b\u304f\u3044\u2014Claude Code\u3067\u7d20\u65e9\u304f\u7279\u5b9a\u3059\u308b<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u65e5\u4ed8\u51e6\u7406\u306e\u30d0\u30b0\u306f\u300c\u8868\u793a\u4e0a\u306f\u6b63\u5e38\u306b\u898b\u3048\u3066\u52d5\u4f5c\u304c\u9593\u9055\u3063\u3066\u3044\u308b\u300d\u3053\u3068\u304c\u591a\u304f\u3001\u539f\u56e0\u306e\u7279\u5b9a\u304c\u96e3\u3057\u3044\u3067\u3059\u3002Claude Code\u3092\u4f7f\u3046\u3068\u3001\u65e5\u4ed8\u30d0\u30b0\u306e\u539f\u56e0\u7279\u5b9a\u30fb\u4fee\u6b63\u30fb\u30c6\u30b9\u30c8\u30b3\u30fc\u30c9\u751f\u6210\u3092\u52b9\u7387\u5316\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<table>\n<thead><tr><th>\u6d3b\u7528\u30b7\u30fc\u30f3<\/th><th>Claude Code\u3078\u306e\u8cea\u554f\u4f8b<\/th><th>\u671f\u5f85\u3055\u308c\u308b\u52b9\u679c<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>\u30d0\u30b0\u7279\u5b9a<\/td><td>\"\u3053\u306e\u65e5\u4ed8\u6bd4\u8f03\u30b3\u30fc\u30c9\u3067\u671f\u5f85\u3057\u305f\u7d50\u679c\u306b\u306a\u3089\u306a\u3044\u539f\u56e0\u3092\u6559\u3048\u3066\uff08\u30b3\u30fc\u30c9\u8cbc\u308a\u4ed8\u3051\uff09\"<\/td><td>\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u30fb0\u59cb\u307e\u308a\u6708\u30fb\u53c2\u7167\u6bd4\u8f03\u306e\u554f\u984c\u3092\u6307\u6458<\/td><\/tr>\n<tr><td>\u6b63\u3057\u3044\u30b3\u30fc\u30c9\u3078\u306e\u4fee\u6b63<\/td><td>\"getTime()\u3092\u4f7f\u3063\u305f\u5b89\u5168\u306a\u65e5\u4ed8\u6bd4\u8f03\u306b\u66f8\u304d\u76f4\u3057\u3066\"<\/td><td>\u4fee\u6b63\u6e08\u307f\u30b3\u30fc\u30c9\u3092\u5373\u5ea7\u306b\u751f\u6210<\/td><\/tr>\n<tr><td>\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u306e\u30c6\u30b9\u30c8<\/td><td>\"\u3053\u306e\u65e5\u4ed8\u8a08\u7b97\u95a2\u6570\u3067\u5883\u754c\u5024\u30c6\u30b9\u30c8\u30b1\u30fc\u30b9\u3092\u66f8\u3044\u3066\"<\/td><td>\u3046\u308b\u3046\u5e74\u30fb\u6708\u672b\u30fb\u5e74\u672b\u306a\u3069\u5883\u754c\u6761\u4ef6\u306e\u30c6\u30b9\u30c8\u3092\u751f\u6210<\/td><\/tr>\n<tr><td>\u30e9\u30a4\u30d6\u30e9\u30ea\u9078\u5b9a<\/td><td>\"day.js\u3068date-fns\u306e\u6bd4\u8f03\u3092\u6559\u3048\u3066\u3002\u30d0\u30f3\u30c9\u30eb\u30b5\u30a4\u30ba\u3068\u6a5f\u80fd\u3067\u6bd4\u8f03\"<\/td><td>\u7528\u9014\u5225\u306e\u30e9\u30a4\u30d6\u30e9\u30ea\u9078\u5b9a\u30a2\u30c9\u30d0\u30a4\u30b9<\/td><\/tr>\n<tr><td>\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u5909\u63db<\/td><td>\"\u3053\u306e\u65e5\u4ed8\u6587\u5b57\u5217\u3092YYYY\/MM\/DD(\u66dc\u65e5)\u5f62\u5f0f\u306b\u5909\u63db\u3059\u308b\u95a2\u6570\u3092\u66f8\u3044\u3066\"<\/td><td>\u6307\u5b9a\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u306e\u30b3\u30fc\u30c9\u3092\u751f\u6210<\/td><\/tr>\n<\/tbody>\n<\/table>\n\n\n\n<p class=\"wp-block-paragraph\">\u7279\u306b\u52b9\u679c\u7684\u306a\u306e\u304c<strong>\u300c\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u306e\u30c6\u30b9\u30c8\u30b3\u30fc\u30c9\u751f\u6210\u300d<\/strong>\u3067\u3059\u3002\u65e5\u4ed8\u51e6\u7406\u306f\u300c1\u670831\u65e5\u306e\u7fcc\u6708\u300d\u300c2\u670829\u65e5\uff08\u3046\u308b\u3046\u5e74\uff09\u300d\u300c\u5e74\u672b\u5e74\u59cb\u3092\u307e\u305f\u3050\u8a08\u7b97\u300d\u306a\u3069\u5883\u754c\u6761\u4ef6\u3067\u30d0\u30b0\u304c\u591a\u3044\u3002Claude Code\u306b\u300c\u3053\u306e\u95a2\u6570\u306e\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u3092\u5217\u6319\u3057\u3066\u3001\u305d\u308c\u305e\u308c\u306e\u30c6\u30b9\u30c8\u30b3\u30fc\u30c9\u3092\u66f8\u3044\u3066\u300d\u3068\u4f9d\u983c\u3059\u308b\u3068\u3001\u898b\u843d\u3068\u3057\u304c\u3061\u306a\u5883\u754c\u6761\u4ef6\u3092\u7db2\u7f85\u3057\u305f\u30c6\u30b9\u30c8\u3092\u81ea\u52d5\u751f\u6210\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<div class=\"balloon-wrap\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/ceo-sugasawa.jpg\" alt=\"\u4ee3\u8868\u83c5\u6fa4\">\n    <span class=\"balloon-name\">\u4ee3\u8868\u83c5\u6fa4<\/span>\n  <\/div>\n  <div class=\"balloon-body\">\u300c\u65e5\u4ed8\u30d0\u30b0\u306f\u982d\u3067\u306f\u7406\u89e3\u3067\u304d\u3066\u3082\u3001\u5b9f\u969b\u306e\u30b3\u30fc\u30c9\u3067\u518d\u73fe\u3059\u308b\u3068\u306a\u305c\u304b\u52d5\u304b\u306a\u3044\u300d\u3068\u3044\u3046\u7d4c\u9a13\u306f\u30a8\u30f3\u30b8\u30cb\u30a2\u306a\u3089\u8ab0\u3082\u304c\u3042\u308a\u307e\u3059\u3002\u305d\u3046\u3044\u3046\u6642\u306fClaude Code\u306b\u30b3\u30fc\u30c9\u3092\u8cbc\u308a\u4ed8\u3051\u3066\u300c\u306a\u305c\u3053\u306e\u7d50\u679c\u306b\u306a\u308b\u304b\u9010\u6b21\u8aac\u660e\u3057\u3066\u300d\u3068\u304a\u9858\u3044\u3059\u308b\u3068\u3001\u5b9f\u884c\u7d50\u679c\u3092\u8ffd\u3044\u306a\u304c\u3089\u539f\u56e0\u3092\u6559\u3048\u3066\u304f\u308c\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n\n<div class=\"balloon-wrap is-right\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/yamazaki-avatar.png\" alt=\"AI\u9b3c\u7ba1\u7406\u5c71\u5d0e\">\n    <span class=\"balloon-name\">AI\u9b3c\u7ba1\u7406\u5c71\u5d0e<\/span>\n  <\/div>\n  <div class=\"balloon-body\">\u300c\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u306e\u30d0\u30b0\u306f\u74b0\u5883\u306b\u3088\u3063\u3066\u518d\u73fe\u3057\u306a\u3044\u300d\u3068\u3044\u3046\u554f\u984c\u304c\u3042\u308a\u307e\u3059\u3002\u958b\u767a\u74b0\u5883\uff08JST\uff09\u3068\u672c\u756a\u74b0\u5883\uff08UTC\uff09\u3067Date()\u306e\u52d5\u4f5c\u304c\u7570\u306a\u308b\u5834\u5408\u3001\u672c\u756a\u3067\u3060\u3051\u30d0\u30b0\u304c\u51fa\u307e\u3059\u3002Claude Code\u306b\u300c\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u3092\u8003\u616e\u3057\u305fDate\u51e6\u7406\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u6559\u3048\u3066\u300d\u3068\u8cea\u554f\u3059\u308b\u3068\u3001\u74b0\u5883\u306b\u4f9d\u5b58\u3057\u306a\u3044\u5b89\u5168\u306a\u5b9f\u88c5\u65b9\u6cd5\u3092\u30a2\u30c9\u30d0\u30a4\u30b9\u3057\u3066\u3082\u3089\u3048\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n\n<div style=\"background:#f8f9fa;border-left:4px solid #6b7280;border-radius:0 8px 8px 0;padding:16px 20px;margin:20px 0;\">\n  <p style=\"margin:0 0 4px;font-size:13px;font-weight:700;color:#6b7280;letter-spacing:1px;\">&#128218; \u7528\u8a9e\u89e3\u8aac<\/p>\n  <p style=\"margin:0;font-size:15px;line-height:1.7;\"><strong>ISO 8601<\/strong>\uff1a\u65e5\u4ed8\u30fb\u6642\u523b\u306e\u56fd\u969b\u6a19\u6e96\u8868\u8a18\u5f62\u5f0f\u3002\u300cYYYY-MM-DDTHH:mm:ss.sssZ\u300d\u306e\u5f62\u5f0f\u3067\u8868\u73fe\u3055\u308c\u308b\u3002\u672b\u5c3e\u306eZ\u306fUTC\uff08\u5354\u5b9a\u4e16\u754c\u6642\uff09\u3092\u610f\u5473\u3057\u3001+09:00\u306e\u3088\u3046\u306a\u30aa\u30d5\u30bb\u30c3\u30c8\u3067\u4ed6\u306e\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u3082\u8868\u73fe\u3067\u304d\u308b\u3002JavaScript\u306eDate.toISOString()\u306fISO 8601\u5f62\u5f0f\u306e\u6587\u5b57\u5217\u3092\u8fd4\u3059\u3002API\u306e\u30ea\u30af\u30a8\u30b9\u30c8\u30fb\u30ec\u30b9\u30dd\u30f3\u30b9\u3067\u306f\u57fa\u672c\u7684\u306b\u3053\u306e\u5f62\u5f0f\u3092\u4f7f\u3046\u3053\u3068\u3067\u3001\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u306e\u8aa4\u89e3\u304c\u751f\u3058\u306b\u304f\u304f\u306a\u308b\u3002<\/p>\n<\/div>\n\n\n\n<div style=\"background:#f0fdf4;border:1px solid #22c55e;border-radius:8px;padding:20px 24px;margin:24px 0;\">\n  <div style=\"display:flex;align-items:center;gap:8px;margin-bottom:12px;\">\n    <span style=\"font-size:18px;\">&#128161;<\/span>\n    <strong style=\"color:#16a34a;font-size:15px;\">\u65e5\u4ed8\u51e6\u7406\u306e\u91cd\u3044\u5b9f\u88c5\u306fday.js\u307e\u305f\u306fdate-fns\u306b\u59d4\u306d\u308b<\/strong>\n  <\/div>\n  <p style=\"margin:0;font-size:15px;line-height:1.8;color:#333;\">\u8907\u96d1\u306a\u65e5\u4ed8\u64cd\u4f5c\uff08\u7e70\u308a\u8fd4\u3057\u4e88\u5b9a\u306e\u8a08\u7b97\u30fb\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u5909\u63db\u30fb\u56fd\u969b\u5316\u8868\u793a\u306a\u3069\uff09\u304c\u5fc5\u8981\u306a\u5834\u5408\u306f\u3001\u30d0\u30f3\u30c9\u30eb\u30b5\u30a4\u30ba\u304c\u7d042KB\u306eday.js\u304b\u3001\u30c4\u30ea\u30fc\u30b7\u30a7\u30a4\u30af\u5bfe\u5fdc\u306edate-fns\u3092\u4f7f\u3046\u3053\u3068\u3092\u304a\u52e7\u3081\u3057\u307e\u3059\u3002\u6a19\u6e96\u306eDate\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3088\u308a\u9065\u304b\u306b\u5c11\u306a\u3044\u30b3\u30fc\u30c9\u3067\u8907\u96d1\u306a\u51e6\u7406\u304c\u66f8\u3051\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n\n<h3 class=\"wp-block-heading\">JavaScript\u3092\u6d3b\u7528\u3057\u305f\u696d\u52d9\u81ea\u52d5\u5316\u30fbAI\u9023\u643a\u306e\u76f8\u8ac7\u306fGENAI\u3078<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Claude Code\u3092\u4f7f\u3063\u305fJavaScript\u696d\u52d9\u30b9\u30af\u30ea\u30d7\u30c8\u4f5c\u6210\u30fb\u81ea\u52d5\u5316\u30b7\u30b9\u30c6\u30e0\u306e\u8a2d\u8a08\u304b\u3089\u5b9f\u88c5\u307e\u3067\u3002AI\u9b3c\u7ba1\u7406\u3067\u30b5\u30dd\u30fc\u30c8\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<div class=\"balloon-wrap\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/ceo-sugasawa.jpg\" alt=\"\u4ee3\u8868\u83c5\u6fa4\">\n    <span class=\"balloon-name\">\u4ee3\u8868\u83c5\u6fa4<\/span>\n  <\/div>\n  <div class=\"balloon-body\">\u300cJavaScript\u3067\u30b9\u30d7\u30ec\u30c3\u30c9\u30b7\u30fc\u30c8\u3084\u65e5\u7a0b\u7ba1\u7406\u3092\u81ea\u52d5\u5316\u3057\u305f\u3044\u300d\u3068\u3044\u3046\u76f8\u8ac7\u3082\u627f\u308a\u307e\u3059\u3002\u65e5\u4ed8\u51e6\u7406\u306e\u5b9f\u88c5\u3067\u3064\u307e\u305a\u3044\u3066\u3044\u308b\u90e8\u5206\u304c\u3042\u308c\u3070\u3001Claude Code\u3092\u6d3b\u7528\u3057\u3066\u4e00\u7dd2\u306b\u89e3\u6c7a\u3057\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n\n<div style=\"background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);border-radius:16px;padding:36px 32px;margin:48px 0 16px;color:#fff;\">\n  <p style=\"font-size:13px;font-weight:700;color:#dc2626;letter-spacing:2px;margin:0 0 12px;\">NEXT STEP<\/p>\n  <p style=\"font-size:22px;font-weight:800;line-height:1.5;margin:0 0 20px;\">\u3053\u306e\u8a18\u4e8b\u306e\u5185\u5bb9\u3092\u3001\u3042\u306a\u305f\u306e\u30d3\u30b8\u30cd\u30b9\u3067<br>\u5b9f\u8df5\u3057\u3066\u307f\u307e\u305b\u3093\u304b\uff1f<\/p>\n  <div style=\"background:rgba(255,255,255,0.06);border:1px solid rgba(255,255,255,0.12);border-radius:12px;padding:24px;max-width:560px;margin:0 auto;\">\n    <p style=\"font-size:13px;color:#dc2626;font-weight:700;margin:0 0 8px;\">AI\u6d3b\u7528\u3092\u81ea\u793e\u3067\u56de\u305b\u308b\u3088\u3046\u306b\u306a\u308a\u305f\u3044\u65b9\u3078<\/p>\n    <p style=\"font-size:20px;font-weight:800;margin:0 0 12px;\">AI\u9b3c\u7ba1\u7406<\/p>\n    <p style=\"font-size:14px;color:rgba(255,255,255,0.75);margin:0 0 20px;line-height:1.7;\">Claude Code\u30fbCowork\u5c0e\u5165\u652f\u63f4\u304b\u3089\u696d\u52d9\u8a2d\u8a08\u30fb\u793e\u5185\u6d78\u900f\u307e\u3067\u5b9f\u8df5\u30d9\u30fc\u30b9\u3067\u4f34\u8d70\u3002\u300c\u81ea\u793e\u3067\u56de\u305b\u308b\u7d44\u7e54\u300d\u309290\u65e5\u3067\u4f5c\u308b\u7d4c\u55b6\u8005\u5411\u3051\u30c8\u30ec\u30fc\u30cb\u30f3\u30b0\u3002<\/p>\n    <div style=\"text-align:center;\">\n      <a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&utm_medium=article&utm_campaign=cc-javascript-date-compare&utm_content=next-step-cta\" target=\"_blank\" rel=\"noopener\" style=\"display:inline-block;background:#dc2626;color:#fff;font-weight:700;font-size:15px;padding:14px 32px;border-radius:30px;text-decoration:none;\">AI\u9b3c\u7ba1\u7406\u3092\u8a73\u3057\u304f\u898b\u308b \u2192<\/a>\n    <\/div>\n  <\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"faq\">\u3088\u304f\u3042\u308b\u8cea\u554f<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Q. JavaScript\u3067\u73fe\u5728\u306e\u65e5\u4ed8\u3092\u300c2026-07-17\u300d\u5f62\u5f0f\u3067\u53d6\u5f97\u3059\u308b\u306b\u306f\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. \u6a19\u6e96\u7684\u306a\u66f8\u304d\u65b9\u306f\u4ee5\u4e0b\u3067\u3059\uff1aconst now = new Date(); const formatted = `${now.getFullYear()}-${String(now.getMonth() + 1).padStart(2, \"0\")}-${String(now.getDate()).padStart(2, \"0\")}` ;\u3002getMonth()\u306f0\u59cb\u307e\u308a\u306a\u306e\u3067\u5fc5\u305a+1\u3059\u308b\u70b9\u306b\u6ce8\u610f\u3057\u3066\u304f\u3060\u3055\u3044\u3002\u3088\u308a\u7c21\u6f54\u306b\u66f8\u304f\u306a\u3089 now.toISOString().split(\"T\")[0] \u3067\u3082UTC\u57fa\u6e96\u306eYYYY-MM-DD\u5f62\u5f0f\u3092\u53d6\u5f97\u3067\u304d\u307e\u3059\uff08\u305f\u3060\u3057JST\u74b0\u5883\u3067\u306f\u5348\u524d9\u6642\u3088\u308a\u524d\u306e\u6642\u523b\u3067\u65e5\u4ed8\u304c\u305a\u308c\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\uff09\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. 2\u3064\u306e\u65e5\u4ed8\u306e\u5dee\u3092\u65e5\u6570\u3067\u53d6\u5f97\u3059\u308b\u306b\u306f\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. Math.floor((date2.getTime() - date1.getTime()) \/ (1000 * 60 * 60 * 24)) \u3067\u8a08\u7b97\u3067\u304d\u307e\u3059\u3002\u30dd\u30a4\u30f3\u30c8\u306f\u4e21\u8005\u3092getTime()\u3067\u30df\u30ea\u79d2\u306b\u5909\u63db\u3057\u3066\u304b\u3089\u5f15\u304d\u7b97\u3057\u30011\u65e5\u306e\u30df\u30ea\u79d2\u6570\uff0886,400,000\uff09\u3067\u5272\u308b\u3053\u3068\u3002Math.floor()\u3067\u6574\u6570\u306b\u5207\u308a\u6368\u3066\u308b\u3053\u3068\u3067\u300c\u5b8c\u5168\u306a1\u65e5\u304c\u4f55\u65e5\u5206\u304b\u300d\u3092\u8a08\u7b97\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. JavaScript\u3067\u6708\u672b\u65e5\u3092\u53d6\u5f97\u3059\u308b\u306b\u306f\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. new Date(year, month + 1, 0).getDate() \u3067\u53d6\u5f97\u3067\u304d\u307e\u3059\u3002\u300c\u7fcc\u6708\u306e0\u65e5\u76ee\u300d\u306f\u524d\u6708\uff08=\u4eca\u6708\uff09\u306e\u672b\u65e5\u3092\u8fd4\u3059JavaScript\u306e\u4ed5\u7d44\u307f\u3092\u6d3b\u7528\u3057\u305f\u30c8\u30ea\u30c3\u30af\u3067\u3059\u3002\u4f8b\u3048\u30707\u6708\u672b\u65e5\u306a\u3089new Date(2026, 7, 0).getDate() \u2192 31\u30022\u6708\u672b\u65e5\uff08\u3046\u308b\u3046\u5e74\u5bfe\u5fdc\uff09\u3082new Date(2026, 2, 0).getDate()\u3067\u6b63\u3057\u304f28\u65e5\u307e\u305f\u306f29\u65e5\u3092\u8fd4\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. \u65e5\u4ed8\u3092getTime()\u3067\u6bd4\u8f03\u3059\u308b\u3068\u3069\u3046\u3044\u3046\u5229\u70b9\u304c\u3042\u308a\u307e\u3059\u304b\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. getTime()\u306fDate\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u30df\u30ea\u79d2\u306e\u6574\u6570\u5024\u306b\u5909\u63db\u3059\u308b\u305f\u3081\u3001\u6570\u5024\u306e\u5927\u5c0f\u6bd4\u8f03\uff08<\u3001>\u3001===\uff09\u304c\u4f7f\u3048\u307e\u3059\u3002Date\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u305d\u306e\u307e\u307e==\u3084===\u3067\u6bd4\u8f03\u3059\u308b\u3068\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u53c2\u7167\u306e\u6bd4\u8f03\u306b\u306a\u308b\u305f\u3081\u3001\u540c\u3058\u65e5\u4ed8\u3067\u3082\u5225\u3005\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u3057\u3066\u751f\u6210\u3057\u305f\u5834\u5408\u306ffalse\u306b\u306a\u308a\u307e\u3059\u3002getTime()\u3067\u30df\u30ea\u79d2\u5909\u63db\u3059\u308c\u3070===\u3067\u6b63\u78ba\u306a\u7b49\u4fa1\u5224\u5b9a\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. new Date(\"2026-07-17\")\u304c\u306a\u305c\u524d\u306e\u65e5\u306b\u306a\u3063\u3066\u3057\u307e\u3046\u306e\u3067\u3059\u304b\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. ISO\u5f62\u5f0f\u306e\u6587\u5b57\u5217\uff08\"2026-07-17\"\uff09\u306fUTC\uff08\u5354\u5b9a\u4e16\u754c\u6642\uff09\u3068\u3057\u3066\u89e3\u91c8\u3055\u308c\u307e\u3059\u3002JST\u306fUTC+9\u6642\u9593\u306e\u305f\u3081\u3001\"2026-07-17\"\u306fJST\u3067\u306f\u300c2026-07-16 09:00:00\uff08\u524d\u65e5\u306e\u5348\u5f8c9\u6642\uff09\u300d\u3068\u306a\u308a\u307e\u3059\u3002\u65e5\u672c\u6642\u9593\u3067\u6307\u5b9a\u3059\u308b\u306b\u306f\"2026-07-17T00:00:00+09:00\"\u3068\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u3092\u660e\u793a\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. Claude Code\u3067\u65e5\u4ed8\u306e\u30d0\u30b0\u3092\u89e3\u6d88\u3059\u308b\u52b9\u679c\u7684\u306a\u8cea\u554f\u65b9\u6cd5\u306f\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. \u30d0\u30b0\u306e\u3042\u308b\u30b3\u30fc\u30c9\u3068\u671f\u5f85\u3059\u308b\u52d5\u4f5c\u30fb\u5b9f\u969b\u306e\u52d5\u4f5c\u3092\u660e\u793a\u3057\u3066\u8cea\u554f\u3059\u308b\u306e\u304c\u52b9\u679c\u7684\u3067\u3059\u3002\u4f8b\uff1a\u300c\u4ee5\u4e0b\u306e\u30b3\u30fc\u30c9\u3067\u30012026-07-17\u3092\u6e21\u3059\u30682026-07-16\u3068\u8fd4\u3063\u3066\u304d\u307e\u3059\u3002\u539f\u56e0\u3068\u4fee\u6b63\u65b9\u6cd5\u3092\u6559\u3048\u3066\u304f\u3060\u3055\u3044\u3002\uff08\u30b3\u30fc\u30c9\u3092\u8cbc\u308a\u4ed8\u3051\uff09\u300d\u3068\u3044\u3046\u3088\u3046\u306b\u3001\u5165\u529b\u30fb\u671f\u5f85\u5024\u30fb\u5b9f\u969b\u306e\u7d50\u679c\u3092\u30bb\u30c3\u30c8\u3067\u4f1d\u3048\u308b\u3068\u3001Claude Code\u304c\u539f\u56e0\u3092\u6b63\u78ba\u306b\u7279\u5b9a\u3057\u3066\u4fee\u6b63\u6848\u3092\u63d0\u793a\u3057\u3066\u304f\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\n      \"@type\": \"Question\",\n      \"name\": \"JavaScript\u3067\u73fe\u5728\u306e\u65e5\u4ed8\u3092\u300c2026-07-17\u300d\u5f62\u5f0f\u3067\u53d6\u5f97\u3059\u308b\u306b\u306f\uff1f\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"\u6a19\u6e96\u7684\u306a\u66f8\u304d\u65b9\u306f\u4ee5\u4e0b\u3067\u3059\uff1aconst now = new Date(); const formatted = `${now.getFullYear()}-${String(now.getMonth() + 1).padStart(2, \\\"0\\\")}-${String(now.getDate()).padStart(2, \\\"0\\\")}` ;\u3002getMonth()\u306f0\u59cb\u307e\u308a\u306a\u306e\u3067\u5fc5\u305a+1\u3059\u308b\u70b9\u306b\u6ce8\u610f\u3057\u3066\u304f\u3060\u3055\u3044\u3002\u3088\u308a\u7c21\u6f54\u306b\u66f8\u304f\u306a\u3089 now.toISOString().split(\\\"T\\\")[0] \u3067\u3082UTC\u57fa\u6e96\u306eYYYY-MM-DD\u5f62\u5f0f\u3092\u53d6\u5f97\u3067\u304d\u307e\u3059\uff08\u305f\u3060\u3057JST\u74b0\u5883\u3067\u306f\u5348\u524d9\u6642\u3088\u308a\u524d\u306e\u6642\u523b\u3067\u65e5\u4ed8\u304c\u305a\u308c\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\uff09\u3002\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"2\u3064\u306e\u65e5\u4ed8\u306e\u5dee\u3092\u65e5\u6570\u3067\u53d6\u5f97\u3059\u308b\u306b\u306f\uff1f\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Math.floor((date2.getTime() - date1.getTime()) \/ (1000 * 60 * 60 * 24)) \u3067\u8a08\u7b97\u3067\u304d\u307e\u3059\u3002\u30dd\u30a4\u30f3\u30c8\u306f\u4e21\u8005\u3092getTime()\u3067\u30df\u30ea\u79d2\u306b\u5909\u63db\u3057\u3066\u304b\u3089\u5f15\u304d\u7b97\u3057\u30011\u65e5\u306e\u30df\u30ea\u79d2\u6570\uff0886,400,000\uff09\u3067\u5272\u308b\u3053\u3068\u3002Math.floor()\u3067\u6574\u6570\u306b\u5207\u308a\u6368\u3066\u308b\u3053\u3068\u3067\u300c\u5b8c\u5168\u306a1\u65e5\u304c\u4f55\u65e5\u5206\u304b\u300d\u3092\u8a08\u7b97\u3067\u304d\u307e\u3059\u3002\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"JavaScript\u3067\u6708\u672b\u65e5\u3092\u53d6\u5f97\u3059\u308b\u306b\u306f\uff1f\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"new Date(year, month + 1, 0).getDate() \u3067\u53d6\u5f97\u3067\u304d\u307e\u3059\u3002\u300c\u7fcc\u6708\u306e0\u65e5\u76ee\u300d\u306f\u524d\u6708\uff08=\u4eca\u6708\uff09\u306e\u672b\u65e5\u3092\u8fd4\u3059JavaScript\u306e\u4ed5\u7d44\u307f\u3092\u6d3b\u7528\u3057\u305f\u30c8\u30ea\u30c3\u30af\u3067\u3059\u3002\u4f8b\u3048\u30707\u6708\u672b\u65e5\u306a\u3089new Date(2026, 7, 0).getDate() \u2192 31\u30022\u6708\u672b\u65e5\uff08\u3046\u308b\u3046\u5e74\u5bfe\u5fdc\uff09\u3082new Date(2026, 2, 0).getDate()\u3067\u6b63\u3057\u304f28\u65e5\u307e\u305f\u306f29\u65e5\u3092\u8fd4\u3057\u307e\u3059\u3002\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"\u65e5\u4ed8\u3092getTime()\u3067\u6bd4\u8f03\u3059\u308b\u3068\u3069\u3046\u3044\u3046\u5229\u70b9\u304c\u3042\u308a\u307e\u3059\u304b\uff1f\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"getTime()\u306fDate\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u30df\u30ea\u79d2\u306e\u6574\u6570\u5024\u306b\u5909\u63db\u3059\u308b\u305f\u3081\u3001\u6570\u5024\u306e\u5927\u5c0f\u6bd4\u8f03\uff08<\u3001>\u3001===\uff09\u304c\u4f7f\u3048\u307e\u3059\u3002Date\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u305d\u306e\u307e\u307e==\u3084===\u3067\u6bd4\u8f03\u3059\u308b\u3068\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u53c2\u7167\u306e\u6bd4\u8f03\u306b\u306a\u308b\u305f\u3081\u3001\u540c\u3058\u65e5\u4ed8\u3067\u3082\u5225\u3005\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u3057\u3066\u751f\u6210\u3057\u305f\u5834\u5408\u306ffalse\u306b\u306a\u308a\u307e\u3059\u3002getTime()\u3067\u30df\u30ea\u79d2\u5909\u63db\u3059\u308c\u3070===\u3067\u6b63\u78ba\u306a\u7b49\u4fa1\u5224\u5b9a\u304c\u3067\u304d\u307e\u3059\u3002\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"new Date(\\\"2026-07-17\\\")\u304c\u306a\u305c\u524d\u306e\u65e5\u306b\u306a\u3063\u3066\u3057\u307e\u3046\u306e\u3067\u3059\u304b\uff1f\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"ISO\u5f62\u5f0f\u306e\u6587\u5b57\u5217\uff08\\\"2026-07-17\\\"\uff09\u306fUTC\uff08\u5354\u5b9a\u4e16\u754c\u6642\uff09\u3068\u3057\u3066\u89e3\u91c8\u3055\u308c\u307e\u3059\u3002JST\u306fUTC+9\u6642\u9593\u306e\u305f\u3081\u3001\\\"2026-07-17\\\"\u306fJST\u3067\u306f\u300c2026-07-16 09:00:00\uff08\u524d\u65e5\u306e\u5348\u5f8c9\u6642\uff09\u300d\u3068\u306a\u308a\u307e\u3059\u3002\u65e5\u672c\u6642\u9593\u3067\u6307\u5b9a\u3059\u308b\u306b\u306f\\\"2026-07-17T00:00:00+09:00\\\"\u3068\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u3092\u660e\u793a\u3057\u3066\u304f\u3060\u3055\u3044\u3002\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Claude Code\u3067\u65e5\u4ed8\u306e\u30d0\u30b0\u3092\u89e3\u6d88\u3059\u308b\u52b9\u679c\u7684\u306a\u8cea\u554f\u65b9\u6cd5\u306f\uff1f\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"\u30d0\u30b0\u306e\u3042\u308b\u30b3\u30fc\u30c9\u3068\u671f\u5f85\u3059\u308b\u52d5\u4f5c\u30fb\u5b9f\u969b\u306e\u52d5\u4f5c\u3092\u660e\u793a\u3057\u3066\u8cea\u554f\u3059\u308b\u306e\u304c\u52b9\u679c\u7684\u3067\u3059\u3002\u4f8b\uff1a\u300c\u4ee5\u4e0b\u306e\u30b3\u30fc\u30c9\u3067\u30012026-07-17\u3092\u6e21\u3059\u30682026-07-16\u3068\u8fd4\u3063\u3066\u304d\u307e\u3059\u3002\u539f\u56e0\u3068\u4fee\u6b63\u65b9\u6cd5\u3092\u6559\u3048\u3066\u304f\u3060\u3055\u3044\u3002\uff08\u30b3\u30fc\u30c9\u3092\u8cbc\u308a\u4ed8\u3051\uff09\u300d\u3068\u3044\u3046\u3088\u3046\u306b\u3001\u5165\u529b\u30fb\u671f\u5f85\u5024\u30fb\u5b9f\u969b\u306e\u7d50\u679c\u3092\u30bb\u30c3\u30c8\u3067\u4f1d\u3048\u308b\u3068\u3001Claude Code\u304c\u539f\u56e0\u3092\u6b63\u78ba\u306b\u7279\u5b9a\u3057\u3066\u4fee\u6b63\u6848\u3092\u63d0\u793a\u3057\u3066\u304f\u308c\u307e\u3059\u3002\"\n      }\n    }\n  ]\n}\n<\/script>\n\n\n","protected":false},"excerpt":{"rendered":"<p>JavaScript\u306eDate()\u3092\u4f7f\u3063\u305f\u65e5\u4ed8\u53d6\u5f97\u30fb\u6bd4\u8f03\u30fb\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u65b9\u6cd5\u3092\u5b8c\u5168\u89e3\u8aac\u3002getTime()\u306b\u3088\u308bms\u6bd4\u8f03\u30fb\u6708\u306f0\u59cb\u307e\u308a\u306e\u843d\u3068\u3057\u7a74\u30fb\u65e5\u4ed8\u5dee\u306e\u8a08\u7b97\u30fb\u3046\u308b\u3046\u5e74\u5224\u5b9a\u307e\u3067\u3002Claude Code\u3092\u4f7f\u3063\u305f\u65e5\u4ed8\u30d0\u30b0\u306e\u30c7\u30d0\u30c3\u30b0\u52b9\u7387\u5316\u3082\u7d39\u4ecb\u3002<\/p>\n","protected":false},"author":1,"featured_media":17652,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"sitemap_hide":"","_veu_custom_css":"","vkexunit_cta_each_option":"","footnotes":"","rank_math_description":"JavaScript\u306eDate()\u3092\u4f7f\u3063\u305f\u65e5\u4ed8\u53d6\u5f97\u30fb\u6bd4\u8f03\u30fb\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u65b9\u6cd5\u3092\u5b8c\u5168\u89e3\u8aac\u3002getTime()\u306b\u3088\u308bms\u6bd4\u8f03\u30fb\u6708\u306f0\u59cb\u307e\u308a\u306e\u843d\u3068\u3057\u7a74\u30fb\u65e5\u4ed8\u5dee\u306e\u8a08\u7b97\u30fb\u3046\u308b\u3046\u5e74\u5224\u5b9a\u307e\u3067\u3002Claude Code\u3092\u4f7f\u3063\u305f\u65e5\u4ed8\u30d0\u30b0\u306e\u30c7\u30d0\u30c3\u30b0\u52b9\u7387\u5316\u3082\u7d39\u4ecb\u3002","rank_math_focus_keyword":"JavaScript \u65e5\u4ed8 \u53d6\u5f97 \u6bd4\u8f03 Date","rank_math_title":"\u30102026\u5e747\u6708\u6700\u65b0\u3011JavaScript\u306e\u65e5\u4ed8\u53d6\u5f97\u30fb\u6bd4\u8f03\u30fb\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u5b8c\u5168\u30ac\u30a4\u30c9\uff5cDate()\u306e\u4f7f\u3044\u65b9\u304b\u3089Claude Code\u6d3b\u7528\u307e\u3067","pending_rewrite_html":"","pending_rewrite_id":"","pending_rewrite_kw":"","pending_rewrite_at":"","pending_rewrite_source":"","pending_rewrite_brief":"","pending_rewrite_evidence":"","approved_rewrite_html":"","approved_rewrite_id":"","approved_rewrite_kw":"","approved_rewrite_at":"","approved_rewrite_by":"","approved_rewrite_brief":"","approved_rewrite_evidence":"","rewrite_tracker_baseline":"","rewrite_tracker_7day":"","rewrite_tracker_14day":"","rewrite_tracker_30day":"","rewrite_tracker_notified":""},"categories":[6,2],"tags":[],"class_list":["post-17653","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-ai-glossary","category-claude-tips"],"_links":{"self":[{"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/posts\/17653","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/comments?post=17653"}],"version-history":[{"count":1,"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/posts\/17653\/revisions"}],"predecessor-version":[{"id":17654,"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/posts\/17653\/revisions\/17654"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/media\/17652"}],"wp:attachment":[{"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/media?parent=17653"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/categories?post=17653"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-json\/wp\/v2\/tags?post=17653"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}