{"id":2794,"date":"2021-04-04T17:42:30","date_gmt":"2021-04-04T08:42:30","guid":{"rendered":"https:\/\/qol-kk.com\/wp2\/?p=2794"},"modified":"2021-04-13T09:50:21","modified_gmt":"2021-04-13T00:50:21","slug":"post-2794","status":"publish","type":"post","link":"https:\/\/qol-kk.com\/wp2\/blog\/2021\/04\/04\/post-2794\/","title":{"rendered":"JavaScript\uff1a\u304a\u624b\u4f1d\u3044\u3057\u3066\u3044\u308b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30b9\u30af\u30fc\u30eb\u3067\u805e\u304b\u308c\u305f\u8cea\u554f\u3010let\/var\/const\u306e\u9055\u3044\u3011"},"content":{"rendered":"<h2>JavaScript\uff1a\u304a\u624b\u4f1d\u3044\u3057\u3066\u3044\u308b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30b9\u30af\u30fc\u30eb\u3067\u805e\u304b\u308c\u305f\u8cea\u554f\u3010let\/var\/const\u306e\u9055\u3044\u3011<\/h2>\n<p>\u6700\u8fd1\u306b\u306a\u308a\u7e01\u3042\u3063\u3066\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30b9\u30af\u30fc\u30eb\u306e\u304a\u624b\u4f1d\u3044\u3092\u3059\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u305f\u3002\u305d\u306e\u751f\u5f92\u3055\u3093\u3068\u3044\u308d\u3044\u308d\u304a\u8a71\u3057\u3066\u3044\u308b\u4e2d\u3067\u51fa\u3066\u304d\u305f\u300e\u3088\u304f\u7406\u89e3\u3067\u304d\u306a\u304b\u3063\u305f\u4e8b\u300f\u306b\u3064\u3044\u3066\u300c\u305d\u3046\u8a00\u3048\u3070\u81ea\u5206\u3082\u6700\u521d\u8a70\u307e\u3063\u305f\u300d\u3068\u611f\u3058\u305f\u3082\u306e\u304c\u3044\u304f\u3064\u304b\u3042\u3063\u305f\u306e\u3067\u3001\u3053\u306e\u969b\u307e\u3068\u3081\u3066\u304a\u3053\u3046\u304b\u3068\u3002<br \/>\n\u5177\u4f53\u7684\u306b\u306f\u3053\u3093\u306a\u5185\u5bb9\u3067\u3059\u3002<\/p>\n<div class=\"paperBox\">\n<ol>\n<li>let \u3068 const \u3068 var \u306f\u4f55\u304c\u9055\u3046\u306e\uff1f&lt;=\u3010\u4eca\u56de\u306e\u5185\u5bb9\u3011<\/li>\n<li><a href=\"https:\/\/qol-kk.com\/wp2\/blog\/2021\/04\/05\/post-2797\/\">function\u3063\u3066\u4f55\uff1f\u3042\u308b\u6642\u3068\u306a\u3044\u6642\u3067\u4f55\u304c\u9055\u3046\u306e\uff1f<\/a><\/li>\n<li><a href=\"https:\/\/qol-kk.com\/wp2\/blog\/2021\/04\/06\/post-2810\/\">\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306f { } \u3067\u56f2\u308f\u308c\u3066\u3044\u308b\u3068\u3044\u3046\u3051\u3069\u3001function(){ } \u306e { } \u306e\u4e2d\u3082\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306a\u306e\uff1f<\/a><\/li>\n<li><a href=\"https:\/\/qol-kk.com\/wp2\/blog\/2021\/04\/12\/post-2821\/\">this. \u3063\u3066\u3069\u3053\u3092\u6307\u3057\u3066\u3044\u308b\u306e\uff1f<\/a><\/li>\n<li><a href=\"https:\/\/qol-kk.com\/wp2\/blog\/2021\/04\/13\/post-2834\/\">JavaScript\u3068Java\u306f\u540c\u3058\u306a\u306e\uff1f<\/a><\/li>\n<\/ol>\n<\/div>\n<h3>let \u3068 const \u3068 var \u306f\u4f55\u304c\u9055\u3046\u306e\uff1f<\/h3>\n<p>\u30d7\u30ed\u30b0\u30e9\u30e0\u3092JS\u304b\u3089\u59cb\u3081\u305f\u4eba\u306f\u591a\u5206\u307f\u3093\u306a\u901a\u308b\u9053\u306a\u306e\u3067\u306f\u306a\u3044\u3067\u3057\u3087\u3046\u304b\u3002<br \/>\n\u5b9a\u6570\u3084\u5909\u6570\u3092\u5ba3\u8a00\u3059\u308b\u3053\u3068\u306f\u300e\u30a8\u30e9\u30fc\u306e\u306a\u3044\u30d7\u30ed\u30b0\u30e9\u30e0\u300f\u3092\u4f5c\u308b\u3046\u3048\u3067\u3082\u3001\u3068\u3066\u3082\u91cd\u8981\u306a\u5de5\u7a0b\u3067\u3059\u3002<br \/>\nJS\u3067\u306f3\u3064\u306e\u5ba3\u8a00\u304c\u4f7f\u308f\u308c\u307e\u3059\u304c\u3001\u4eca\u5f8c\u306f2\u3064\u306b\u307e\u3068\u307e\u3063\u3066\u3044\u304f\u3068\u601d\u308f\u308c\u307e\u3059\u3002<\/p>\n<div class=\"borderBox\">\n<ol>\n<li>\u5b9a\u6570\u3092\u5ba3\u8a00\u3059\u308bconst\uff08\u30b3\u30f3\u30b9\u30c8\uff09<\/li>\n<li>\u5909\u6570\u3092\u5ba3\u8a00\u3059\u308blet\uff08\u30ec\u30c3\u30c8\uff09<\/li>\n<li>\u5b9a\u6570\u3067\u3082\u5909\u6570\u3067\u3082\u95a2\u4fc2\u306a\u304f\u5ba3\u8a00\u3059\u308bvar\uff08\u30d0\u30fc\uff09<\/li>\n<\/ol>\n<\/div>\n<p>Google\u5148\u751f\u306b\u805e\u3044\u3066\u51fa\u3066\u304f\u308b\u60c5\u5831\u3060\u3068var \u304c\u4e00\u756a\u591a\u3044\u304b\u306a\u3068\u601d\u3044\u307e\u3059\u304c\u3001\u30c6\u30ad\u30b9\u30c8\u7cfb(\u66f8\u7c4d)\u3060\u3068 let \u306e\u51fa\u73fe\u7387\u304c\u9ad8\u304f\u306a\u308a\u307e\u3059\u3002<br \/>\n\u3053\u308c\u306f\u3001let \u3084const \u304c2015\u5e746\u6708\u306b\u6a19\u6e96\u5316\u3055\u308c\u305f JavaScript\u306e\u300cECMAScript 2015\uff08<b>ES6<\/b>\uff09\u300d\u304b\u3089\u4f7f\u3048\u308b\u3088\u3046\u306b\u306a\u3063\u305f\u4e8b\u306b\u7531\u6765\u3057\u307e\u3059\u3002<br \/>\n\u30cd\u30c3\u30c8\u4e0a\u306e\u60c5\u5831\u306f\u3082\u3063\u3068\u524d\u304b\u3089\u84c4\u7a4d\u3055\u308c\u3066\u3044\u308b\u306e\u3067\u3001var\u3067\u5ba3\u8a00\u3057\u3066\u3044\u308b\u53c2\u8003\u4e8b\u4f8b\u3092\u76ee\u306b\u3059\u308b\u7387\u304c\u9ad8\u307e\u308a\u307e\u3059\u3002<\/p>\n<h4>\u300cvar\u306f\u4f7f\u308f\u306a\u3044\u3088\u3046\u306b\u3057\u3088\u3046\u300d\u304c\u57fa\u672c\u7684\u306a\u6d41\u308c<\/h4>\n<p>ES6\u3088\u308a\u524d\u3067\u306f\u5ba3\u8a00\u306fvar\u3057\u304b\u3042\u308a\u307e\u305b\u3093\u3067\u3057\u305f\u3002\u305d\u306e\u305f\u3081\u3001\u5b9a\u6570\u3067\u3042\u308c\u5909\u6570\u3067\u3042\u308cvar\u3092\u5229\u7528\u3057\u3066\u3044\u307e\u3057\u305f\u3002<br \/>\n\u3057\u304b\u3057\u3010\u30d6\u30ed\u30c3\u30af\u30ec\u30d9\u30eb\u306e\u30b9\u30b3\u30fc\u30d7\u306b\u5bfe\u5fdc\u3067\u304d\u308blet\u3011\u3068\u3010\u5909\u66f4\u3092\u62d2\u5426\u3059\u308bconst\u3011\u304c\u3067\u304d\u305f\u305f\u3081\u300clet\u3068const\u3092\u4f7f\u3063\u3066var\u306f\u3084\u3081\u3088\u3046\u300d\u3068\u3044\u3046\u6d41\u308c\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002<br \/>\n\u305d\u308c\u3067\u3082\uff08\u79c1\u3092\u542b\u3081\uff092015\u5e74\u4ee5\u524d\u304b\u3089\u30b9\u30af\u30ea\u30d7\u30c8\u66f8\u3044\u3066\u3044\u308b\u4eba\u306f\u3064\u3044\u3064\u3044\u300cvar\u300d\u3063\u3066\u5ba3\u8a00\u3057\u3066\u3057\u307e\u3046\u3068\u601d\u3044\u307e\u3059\u304c\u3002\u624b\u304c\u52dd\u624b\u306bvar\u3063\u3066\u6253\u3063\u3066\u308b\u3093\u3067\u3059\u3088\u306d\u3002<\/p>\n<h3>\u30d6\u30ed\u30c3\u30af\u30ec\u30d9\u30eb\u306e\u30b9\u30b3\u30fc\u30d7\u3063\u3066\uff1f<\/h3>\n<p><a href=\"http:\/\/www.rpm.or.jp\/home\/pon\/CmmLang\/node99.html\">\u3053\u3053<\/a>\u3068<a href=\"https:\/\/www.codetd.com\/ja\/article\/12584877\">\u3053\u3053<\/a>\u3068<a href=\"https:\/\/tsudoi.org\/weblog\/4907\/\">\u3053\u3053<\/a>\u3092\u53c2\u7167\u3057\u3066\u304f\u3060\u3055\u3044\u3002\u3053\u308c\u3067\u611f\u899a\u306f\u3064\u304b\u3081\u308b\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n<pre class=\"lang:default decode:true\">\/\/test.js\u30d5\u30a1\u30a4\u30eb\u5185\u3060\u3068\u3057\u3066\r\n\r\n  \/\/ \u30b0\u30ed\u30fc\u30d0\u30eb\u5909\u6570\r\n  var test_a = 10;\r\n  \r\n  \/\/\u30ed\u30fc\u30ab\u30eb\u5909\u6570\r\n  let test_b = 10;\r\n\r\n  function test() {\r\n    \/\/test\u95a2\u6570\u30d6\u30ed\u30c3\u30af\u5185\r\n    var test_c = 100;\r\n    let test_d = 100;\r\n  }\r\n\r\n  console.log(test_a);\r\n    \/\/\u7d50\u679c =&gt; 10\r\n  console.log(test_b);\r\n    \/\/\u7d50\u679c =&gt; 10\r\n  console.log(test_c);\r\n    \/\/\u7d50\u679c =&gt; 100 \u203bfunction\u5185\u3067\u4f5c\u6210\u3057\u305f\u5909\u6570\u3067\u3082function\u306e\u5916\u3067\u547c\u3073\u51fa\u305b\u308b\r\n  console.log(test_d);\r\n    \/\/\u7d50\u679c =&gt; \u30a8\u30e9\u30fc:not defined \u203b\u540c\u3058\u30d6\u30ed\u30c3\u30af\u30ec\u30d9\u30eb\u5185\u306b test_d \u306f\u5b58\u5728\u3057\u306a\u3044<\/pre>\n<p>function\u5185\u3067\u5ba3\u8a00\u3057\u305f\u5834\u5408\u3001var\u3067\u5ba3\u8a00\u3059\u308b\u3068function\u306e\u5916\u3067\u4f7f\u3046\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u304c\u3001let\u3067\u5ba3\u8a00\u3057\u305f\u5834\u5408\u306f\u3053\u308c\u304c\u3067\u304d\u307e\u305b\u3093\u3002<br \/>\ntest.js\u306e\u30b5\u30f3\u30d7\u30eb\u30b3\u30fc\u30c9\u3092\u898b\u3066\u307f\u308b\u3068\u3001let \u3067\u5ba3\u8a00\u3057\u305f\u3010test_b\u3011\u306f\u30c8\u30c3\u30d7\u30ec\u30d9\u30eb\u306b\u5b58\u5728\u3057\u3001\u30ed\u30b0\u8a18\u9332\u30d1\u30fc\u30c8\u3082\u30c8\u30c3\u30d7\u30ec\u30d9\u30eb\u306b\u5b58\u5728\u3057\u307e\u3059\u3002<br \/>\n\u3057\u304b\u3057\u3010test_d\u3011\u306ftest\u95a2\u6570(function test())\u5185\u306b\u5b58\u5728\u3057\u3066\u3044\u3066\u3001\u30ed\u30b0\u8a18\u8f09\u30d1\u30fc\u30c8\u3068\u7570\u306a\u308b\u30d6\u30ed\u30c3\u30af\u30ec\u30d9\u30eb\u306b\u5b58\u5728\u3057\u3066\u3044\u307e\u3059\u3002<br \/>\n\u305d\u306e\u305f\u3081\u300c\u540c\u3058\u968e\u5c64\u306b\u3044\u306a\u3044 = test_d\u306a\u3093\u3066\u5909\u6570\u306f\u77e5\u3089\u306a\u3044\u300d\u3068\u306a\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<pre class=\"lang:default decode:true\">\/\/test.js\u30d5\u30a1\u30a4\u30eb\u5185\u306b\u4e2d\u8eab\u3092\u4e0b\u306b\u5165\u66ff\u3048\r\nlet num = 2;\r\nfunction test(){\r\n  if (num == 1){\r\n    num = 10;\r\n  }else{\r\n    num = 20;\r\n  }\r\n  return(num);\r\n}\r\nconsole.log(test());<\/pre>\n<p>\u3061\u306a\u307f\u306b\u3001\u3053\u306e\u3088\u3046\u306b\u8a18\u8f09\u3059\u308b\u3068\u30ed\u30b0\u306b\u306f20\u3092\u8a18\u8f09\u3057\u307e\u3059\u3002<\/p>\n<pre class=\"\">let num = 2;\r\nfunction test(){\r\n  let num2 = 0;\r\n  if (num == 1){\r\n    num2 = 10;\r\n  }else{\r\n    num2 = 20;\r\n  }\r\n  return(num2);\r\n}\r\nconsole.log(test());<\/pre>\n<p>\u3053\u306e\u3088\u3046\u306b\u8a18\u8f09\u3057\u3066\u308220\u3092\u8a18\u9332\u3057\u307e\u3059\u304c\u3001<\/p>\n<pre class=\"\">let num = 2;\r\nfunction test(){\r\n  var num = 0;\r\n\uff08\u4ee5\u4e0b\u7565\uff09<\/pre>\n<p>\u3068\u3059\u308b\u3068\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3057\u307e\u3059\u3002\u3053\u308c\u306flet\u304c\u518d\u5ba3\u8a00\u7981\u6b62\u3068\u306a\u3063\u3066\u3044\u308b\u304b\u3089\u3067\u3059\u3002<\/p>\n<h3>\u307e\u3068\u3081<\/h3>\n<p>\u7d9a\u3051\u3066\u66f8\u3053\u3046\u3068\u601d\u3044\u307e\u3057\u305f\u304c\u3001\u3053\u306e\u30cd\u30bf\u3060\u3051\u3067\u9577\u304f\u306a\u3063\u3066\u3057\u307e\u3063\u305f\u306e\u3067\u7d9a\u304d\u306f\u307e\u305f\u5225\u306e\u8a18\u4e8b\u3067\u3002<\/p>\n<div class=\"borderBox\">\n<ol>\n<li>let \u3068 const \u3068 var \u306f\u4f55\u304c\u9055\u3046\u306e\uff1f&lt;=\u3010\u4eca\u56de\u306e\u5185\u5bb9\u3011<\/li>\n<li><a href=\"https:\/\/qol-kk.com\/wp2\/blog\/2021\/04\/05\/post-2797\/\">function\u3063\u3066\u4f55\uff1f\u3042\u308b\u6642\u3068\u306a\u3044\u6642\u3067\u4f55\u304c\u9055\u3046\u306e\uff1f<\/a><\/li>\n<li><a href=\"https:\/\/qol-kk.com\/wp2\/blog\/2021\/04\/06\/post-2810\/\">\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306f { } \u3067\u56f2\u308f\u308c\u3066\u3044\u308b\u3068\u3044\u3046\u3051\u3069\u3001function(){ } \u306e { } \u306e\u4e2d\u3082\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306a\u306e\uff1f<\/a><\/li>\n<li><a href=\"https:\/\/qol-kk.com\/wp2\/blog\/2021\/04\/12\/post-2821\/\">this. \u3063\u3066\u3069\u3053\u3092\u6307\u3057\u3066\u3044\u308b\u306e\uff1f<\/a><\/li>\n<li><a href=\"https:\/\/qol-kk.com\/wp2\/blog\/2021\/04\/13\/post-2834\/\">JavaScript\u3068Java\u306f\u540c\u3058\u306a\u306e\uff1f<\/a><\/li>\n<\/ol>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>JavaScript\uff1a\u304a\u624b\u4f1d\u3044\u3057\u3066\u3044\u308b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30b9\u30af\u30fc\u30eb\u3067\u805e\u304b\u308c\u305f\u8cea\u554f\u3010let\/var\/const\u306e\u9055\u3044\u3011 \u6700\u8fd1\u306b\u306a\u308a\u7e01\u3042\u3063\u3066\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30b9\u30af\u30fc\u30eb\u306e\u304a\u624b\u4f1d\u3044\u3092\u3059\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u305f\u3002\u305d\u306e\u751f\u5f92\u3055\u3093\u3068\u3044\u308d\u3044\u308d\u304a\u8a71\u3057\u3066\u3044\u308b 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