{"description":"\u7a7a\u6587\u5b57\u5224\u5b9a\u3092\u884c\u3046\u7c21\u5358\u306a\u65b9\u6cd5\u3067\u3059\u304c\u3001JavaScript\u3067\u306f if \u5206\u306e\u4e2d\u3067\u3001\u7a7a\u6587\u5b57\u3092\u8a55\u4fa1\u3059\u308b\u3068 false \u306b\u306a\u308a\u307e\u3059\u3002 \u3068\u3044\u3046\u3053\u3068\u3067\u3001\u4e0b\u8a18\u3060\u3051\u3067\u5224\u5b9a\u304c\u53ef\u80fd\u3067\u3059\u3002 var str=\"\"; if ( str ){ alert(\"\u7a7a\u6587\u5b57\u3067\u306a\u3044\"); }else{ alert(\"\u7a7a\u6587\u5b57\u3067\u3042\u308b\"); } \u3061\u306a\u307f\u306b\u3001[JavaScript] \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304cnull\u3084undefind\u3067\u306a\u3044\u304b\u8a55\u4fa1\u3059\u308b\u3002 - \u3046\u306a\u306e\u65e5\u8a18 \u3092\u53c2\u8003\u306b\u3055\u305b\u3066\u3082\u3089\u3063\u305f\u3068\u3053\u308d\u3001\u5024\u3054\u3068\u3067if\u306e\u8a55\u4fa1\u3092\u3059\u308b\u3068\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308b\u3088\u3046\u3067\u3059\u3002 \u5024 :if\u3067\u8a55\u4fa1\u3057\u305f\u7d50\u679c Object :true undefined:false null :false\u2026","type":"rich","url":"https://3ryupg.hatenablog.com/entry/2012/11/11/003800","version":"1.0","blog_url":"https://3ryupg.hatenablog.com/","blog_title":"3\u6d41\u30d7\u30ed\u30b0\u30e9\u30de\u306e\u30e1\u30e2\u66f8\u304d","published":"2012-11-11 00:38:00","provider_url":"https://hatena.blog","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2F3ryupg.hatenablog.com%2Fentry%2F2012%2F11%2F11%2F003800\" title=\"(JavaScript)\u7a7a\u6587\u5b57\u5224\u5b9a\u3092\u884c\u3046\u7c21\u5358\u306a\u65b9\u6cd5 - 3\u6d41\u30d7\u30ed\u30b0\u30e9\u30de\u306e\u30e1\u30e2\u66f8\u304d\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","image_url":null,"title":"(JavaScript)\u7a7a\u6587\u5b57\u5224\u5b9a\u3092\u884c\u3046\u7c21\u5358\u306a\u65b9\u6cd5","author_url":"https://blog.hatena.ne.jp/deloreanmc12/","provider_name":"Hatena Blog","height":"190","author_name":"deloreanmc12","width":"100%","categories":["Web\u304c\u3089\u307f"]}