{"width":"100%","url":"https://atsukanrock.hatenablog.com/entry/20090310/1236678752","blog_url":"https://atsukanrock.hatenablog.com/","categories":["JavaScript"],"provider_url":"https://hatena.blog","type":"rich","published":"2009-03-10 18:52:32","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fatsukanrock.hatenablog.com%2Fentry%2F20090310%2F1236678752\" title=\"JavaScript\u306ein\u6f14\u7b97\u5b50 - atsukanrock\u306e\u30d6\u30ed\u30b0\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","author_url":"https://blog.hatena.ne.jp/atsukanrock/","version":"1.0","image_url":null,"title":"JavaScript\u306ein\u6f14\u7b97\u5b50","blog_title":"atsukanrock\u306e\u30d6\u30ed\u30b0","height":"190","author_name":"atsukanrock","description":"JavaScript\u3067\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u30d7\u30ed\u30d1\u30c6\u30a3\u304c\u5b58\u5728\u3059\u308b\u304b\u3069\u3046\u304b\u3092\u5224\u5b9a\u3059\u308b\u306e\u306b\u3001in\u6f14\u7b97\u5b50\u3068\u3044\u3046\u306e\u304c\u3042\u308b\u3002\u6065\u305a\u304b\u3057\u306a\u304c\u3089\u3001\u4eca\u65e5\u521d\u3081\u3066\u77e5\u3063\u305f\u3002 \u4ee5\u4e0b\u306e\u3088\u3046\u306b\u4f7f\u7528\u3059\u308b\u3002 alert(\"hoge\" in { \"hoge\": null }); // alert \"true\" alert(\"fuga\" in { \"hoge\": null }); // alert \"false\" \u305f\u3060\u3057\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u81ea\u5206\u3067\u8ffd\u52a0\u3057\u305f\u4ee5\u5916\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u306b\u3064\u3044\u3066\u3082true\u3092\u8fd4\u3059\u3053\u3068\u306b\u6ce8\u610f\u3059\u308b\u3002 alert(\"hasOwnProperty\" in {}); // alert \"true\"","provider_name":"Hatena Blog"}