{"image_url":null,"blog_title":"Mitsuyuki.Shiiba","height":"190","published":"2020-05-18 22:01:01","title":"JavaScript\u306e\u52c9\u5f37\u4e2d\uff1a\u305d\u306e\uff12 Expressions and Operators","author_url":"https://blog.hatena.ne.jp/bufferings/","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fbufferings.hatenablog.com%2Fentry%2F2020%2F05%2F18%2F220101\" title=\"JavaScript\u306e\u52c9\u5f37\u4e2d\uff1a\u305d\u306e\uff12 Expressions and Operators - Mitsuyuki.Shiiba\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","width":"100%","url":"https://bufferings.hatenablog.com/entry/2020/05/18/220101","categories":["JavaScript"],"type":"rich","author_name":"bufferings","version":"1.0","provider_name":"Hatena Blog","provider_url":"https://hatena.blog","blog_url":"https://bufferings.hatenablog.com/","description":"\u306f\u3044\u3001\u6628\u65e5\u306e\u7d9a\u304d\u3002 bufferings.hatenablog.com ## Ch.4 Expressions and Operators ### 4.4.1 Conditional Property Access ES2020 \u3067\u4ee5\u4e0b\u306e2\u3064\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u30a2\u30af\u30bb\u30b9\u5f0f\u304c\u8ffd\u52a0\u3055\u308c\u305f\uff1a expression ?. identifier expression ?. [ expression ] \u666e\u901a\u306e\u30d7\u30ed\u30d1\u30c6\u30a3\u30a2\u30af\u30bb\u30b9\u306e\u5834\u5408\u306b\u306f\u3001\u5de6\u5074\u306e\u5f0f\u304c null \u304b undefined \u3060\u3068 TypeError \u304c\u51fa\u308b\u3002 ?. \u3084 ?.[] \u3092\u4f7f\u3048\u3070\u30a8\u30e9\u30fc\u306f\u51fa\u305a\u306b undefined \u304c\u8fd4\u3055\u308c\u308b\u3002 Welcome \u2026"}