{"provider_url":"https://hatena.blog","version":"1.0","title":"Effective JavaScript 3","type":"rich","image_url":null,"published":"2014-07-06 12:24:33","author_url":"https://blog.hatena.ne.jp/shigemk2/","width":"100%","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fwww.shigemk2.com%2Fentry%2F2014%2F07%2F06%2FEffective_JavaScript_3\" title=\"Effective JavaScript 3 - by shigemk2\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","blog_title":"by shigemk2","url":"https://www.shigemk2.com/entry/2014/07/06/Effective_JavaScript_3","blog_url":"https://www.shigemk2.com/","height":"190","categories":["JavaScript"],"provider_name":"Hatena Blog","author_name":"shigemk2","description":"\u578b\u30a8\u30e9\u30fc\u306f\u6697\u9ed9\u306e\u578b\u5f37\u5236\u306b\u3088\u3063\u3066\u96a0\u3055\u308c\u308b\u3053\u3068\u304c\u3042\u308b +\u6f14\u7b97\u5b50\u306f\u5f15\u6570\u306e\u578b\u306b\u3088\u3063\u3066\u3001\u52a0\u7b97\u307e\u305f\u306f\u6587\u5b57\u5217\u306e\u9023\u7d50\u3092\u884c\u3046\u3088\u3046\u306b\u591a\u91cd\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306fvalueOf\u306b\u3088\u3063\u3066\u6570\u5024\u306b\u5909\u63db\u3055\u308c\u3001toString\u306b\u3088\u3063\u3066\u6587\u5b57\u5217\u306b\u5909\u63db\u3055\u308c\u308b valueOf\u30e1\u30bd\u30c3\u30c9\u3092\u6301\u3064\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306f\u3001\u305d\u306evalueOf\u306b\u3088\u3063\u3066\u751f\u6210\u3055\u308c\u308b\u6570\u5024\u306e\u6587\u5b57\u5217\u8868\u73fe\u3092\u63d0\u4f9b\u3059\u308btoString\u30e1\u30bd\u30c3\u30c9\u3092\u5b9f\u88c5\u3059\u3079\u304d\u3067\u3042\u308b \u672a\u5b9a\u7fa9\u306e\u5024\u3092\u30c6\u30b9\u30c8\u3059\u308b\u306b\u306f\u771f\u507d\u6027\u3067\u306f\u306a\u304ftypeof\u304bundefined\u306e\u6bd4\u8f03\u3067\u884c\u3046"}