{"id":107698,"date":"2021-05-10T15:49:20","date_gmt":"2021-05-10T06:49:20","guid":{"rendered":"http:\/\/www.key-p.com\/blog\/staff\/?p=107698"},"modified":"2021-05-22T18:14:39","modified_gmt":"2021-05-22T09:14:39","slug":"nullish-coalecing%e3%82%92%e4%bd%bf%e3%81%a3%e3%81%a6%e3%81%bf%e3%82%8b","status":"publish","type":"post","link":"https:\/\/www.key-p.com\/blog\/staff\/archives\/107698","title":{"rendered":"Nullish coalescing\u3092\u4f7f\u3063\u3066\u307f\u308b"},"content":{"rendered":"

\n\u6e9d\u7551\u3067\u3059\u3002
\n
\n\u672c\u5f53\u306b\u8efd\u3044\u30cd\u30bf\u3092\u3053\u308c\u304b\u3089\u6570\u8a18\u4e8b\u66f8\u3044\u3066\u3044\u304d\u307e\u3059\u3002
\n
\n\u524d\u56de<\/a>\u3001Proxy\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u3064\u3044\u3066\u66f8\u3044\u305f\u969b\u3001
\n\u4f7f\u7528\u4f8b\u3068\u3057\u3066\u300c\u7279\u5b9a\u306e\u30c7\u30fc\u30bf\u306e\u3068\u304d\u306e\u51fa\u529b\u3092\u7d71\u4e00\u3057\u305f\u3044\u300d\u306e\u3088\u3046\u306a\u30b1\u30fc\u30b9\u3092\u66f8\u304d\u307e\u3057\u305f\u3002
\n
\n\u304c\u3001\u4f3c\u305f\u3088\u3046\u306a\u30b1\u30fc\u30b9\u3092\u89e3\u6d88\u3067\u304d\u305d\u3046\u306a\u3082\u306e\u304c\u3001ES2020\u3067\u8ffd\u52a0\u3055\u308c\u3066\u3044\u307e\u3057\u305f\u3002
\n\u3068\u3044\u3046\u3053\u3068\u3067\u3001\u300cNullish coalescing\u300d\u306e\u7d39\u4ecb\u3002
\n
\n

Nullish coalescing<\/h4>\nNullish coalescing<\/a>
\n
\n\u8aac\u660e\u3092\u5f15\u7528\u3059\u308b\u3068\u3001
\n<\/p>\n

> Null \u5408\u4f53\u6f14\u7b97\u5b50 (??) \u306f\u8ad6\u7406\u6f14\u7b97\u5b50\u306e\u4e00\u7a2e\u3067\u3059\u3002\u3053\u306e\u6f14\u7b97\u5b50\u306f\u5de6\u8fba\u304c null \u307e\u305f\u306f undefined \u306e\u5834\u5408\u306b\u53f3\u306e\u5024\u3092\u8fd4\u3057\u3001\u305d\u308c\u4ee5\u5916\u306e\u5834\u5408\u306b\u5de6\u306e\u5024\u3092\u8fd4\u3057\u307e\u3059\u3002<\/p><\/blockquote>\n

\n\u3068\u3044\u3046\u3053\u3068\u3067\u3059\u3002
\n\u30ea\u30f3\u30af\u5148\u306e\u4f8b\u3067\u3001\u4f7f\u7528\u65b9\u6cd5\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002
\n
\n

\/\/ (1)\nconst foo = null ?? 'default string'\nconsole.log(foo) \/\/ default string\n\n\/\/ (2)\nconst baz = 0 ?? 42\nconsole.log(baz) \/\/ 0<\/pre>\n\u6f14\u7b97\u5b50\u306f\u300c??\u300d\u3067\u3059\u3002
\n
\n(1)\u306f\u5de6\u8fba\u304c\u300cnull\u300d\u306a\u306e\u3067\u3001\u53f3\u306edefault string\u3068\u306a\u308a\u307e\u3059\u3002
\n(2)\u306f\u300c0\u300d\u306fnull or undefined\u3067\u306f\u306a\u3044\u306e\u3067\u3001\u305d\u306e\u307e\u307e0\u3068\u306a\u308a\u307e\u3059\u3002
\n
\n\u4e09\u9805\u6f14\u7b97\u5b50\u3068\u306f\u9055\u3063\u3066\u3001null\u304bundefined\u3068\u3044\u3046\u70b9\u306f\u6ce8\u610f\u3067\u3059\u306d\u3002
\n
\n
\u4f7f\u3044\u6240<\/h4>\n\u524d\u56deProxy\u3067\u3084\u3063\u305f\u30b1\u30fc\u30b9\u306f\u300c\u7279\u5b9a\u306e\u6587\u5b57\u306a\u3089\u4e00\u5f8b\u3067\u8868\u793a\u3092\u5909\u3048\u305f\u3044\u300d\u3068\u3044\u3063\u305f\u3082\u306e\u3067\u3057\u305f\u3002
\n
\n\u5358\u7d14\u306b\u30c7\u30fc\u30bf\u4e2d\u306bnull\u304c\u542b\u307e\u308c\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u3001\u8868\u793a\u3092\u5909\u3048\u305f\u3044\u5834\u5408\u306a\u3089\u3001
\n\u4eca\u56de\u306eNullish coalescing\u3067\u4e8b\u8db3\u308a\u305d\u3046\u3067\u3059\u3002
\n
\n
\/\/ null\u306f\u7a7a\u6587\u5b57\u306b\u3059\u308b\nconst rows = data.map(v => `<li>${v.temp ?? ''}<\/li>`)<\/pre>\n\u30bb\u30f3\u30b5\u30fc\u304b\u3089\u53d6\u5f97\u3059\u308b\u5024\u306a\u3069\u3001\u6b20\u640d\u5024\u304cnull\u306b\u306a\u308b\u3088\u3046\u306a\u30b1\u30fc\u30b9\u306f\u5341\u5206\u306b\u8003\u3048\u3089\u308c\u308b\u3068\u601d\u3044\u307e\u3059\u3002
\n
\n\u5358\u7d14\u306a\u4f7f\u7528\u4f8b\u3092\u7d39\u4ecb\u3057\u307e\u3057\u305f\u304c\u3001\u540c\u3058\u304fES2020\u3067\u8ffd\u52a0\u3055\u308c\u305f\u300cOptional chaining\u300d\u306a\u3093\u304b\u3068\u3082\u7d44\u307f\u5408\u308f\u305b\u304c\u52b9\u304d\u307e\u3059\u3002
\nOptional chaining<\/a>
\n
\nES2020\u3068\u65b0\u3057\u3044\u69cb\u6587\u3067\u306f\u3042\u308a\u307e\u3059\u304c\u3001\u4f7f\u3048\u308b\u3068\u3053\u308d\u306f\u4f7f\u3063\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u6e9d\u7551\u3067\u3059\u3002 \u672c\u5f53\u306b\u8efd\u3044\u30cd\u30bf\u3092\u3053\u308c\u304b\u3089\u6570\u8a18\u4e8b\u66f8\u3044\u3066\u3044\u304d\u307e\u3059\u3002 \u524d\u56de\u3001Proxy\u30aa\u30d6 … \u7d9a\u304d\u3092\u8aad\u3080 →<\/span><\/a><\/p>\n","protected":false},"author":33,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[16],"tags":[],"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/posts\/107698"}],"collection":[{"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/users\/33"}],"replies":[{"embeddable":true,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/comments?post=107698"}],"version-history":[{"count":7,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/posts\/107698\/revisions"}],"predecessor-version":[{"id":107719,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/posts\/107698\/revisions\/107719"}],"wp:attachment":[{"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/media?parent=107698"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/categories?post=107698"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.key-p.com\/blog\/staff\/wp-json\/wp\/v2\/tags?post=107698"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}