{"description":"JavaScript\u306e\u60aa\u9b54\u7684\u306a\u632f\u308b\u821e\u3044\u306e\u4e00\u3064\u306bundefined\u304c\u3042\u308b\u3068\u601d\u3046\u3002 javascript\u306b\u306f\u5b58\u5728\u3059\u308bundefined\u3068\u5b58\u5728\u3057\u306a\u3044undefined\u304c\u3042\u308b\u3057\u3001\u305d\u308c\u306f\u3064\u307e\u308a [undefined].length => 1 \u3060\u2014 \u4ffa\u306f\u5e73\u6c17\u3060\u3088 (@mizchi) 2014, 4\u6708 22 JavaScript\u3001[undefined].length => 1 \u3067 arr = []; arr[0] = undefined; \u3060\u3051\u3069\u3001\u3053\u306e\u3068\u304d\u524d\u8005\u306eundefined\u3068\u5f8c\u8005\u306eundefined\u306f\u6027\u8cea\u7684\u306b\u306f\u5225\u7269\u3067\u3059\u3088\u2014 \u4ffa\u306f\u5e73\u6c17\u3060\u3088 (@mizchi) 2014, 4\u6708 22 \u3082\u3046\u4e00\u3064\u306e\u4f8b\u3068\u3057\u3066\u3001\u2026","url":"https://mizchi.hatenablog.com/entry/2014/04/22/204705","type":"rich","version":"1.0","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fmizchi.hatenablog.com%2Fentry%2F2014%2F04%2F22%2F204705\" title=\"JavaScript\u306e\u751f\u304d\u3066\u308bundefined\u3068\u6b7b\u3093\u3067\u308bundefined - mizchi&#39;s blog\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","provider_url":"https://hatena.blog","categories":[],"width":"100%","author_name":"mizchi","author_url":"https://blog.hatena.ne.jp/mizchi/","blog_title":"mizchi's blog","blog_url":"https://mizchi.hatenablog.com/","published":"2014-04-22 20:47:05","title":"JavaScript\u306e\u751f\u304d\u3066\u308bundefined\u3068\u6b7b\u3093\u3067\u308bundefined","height":"190","provider_name":"Hatena Blog","image_url":null}