回答編集履歴
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回答を詳細化
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CHANGED
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@@ -14,13 +14,13 @@
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xxx: function(){}//xxxは値を関数にとるプロパティ名
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}
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};
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({
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xxx: function(){}//xxxは値を関数にとるプロパティ名
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})
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});
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//ブロックスコープを定義する{}
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@@ -31,3 +31,63 @@
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}
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```
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---
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下記は何れもECMA Script 2015で導入された構文です.
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`({})`記法はオブジェクトを返すアロー関数を定義する際に使います.
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```JavaScript
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var f = () => ({//このカッコはオブジェクトのカッコ
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aaa: "あああ",
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xxx: function(){}
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});
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var g = () => {//このカッコはブロックスコープのカッコ
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const a = 1;
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return a;
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}
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```
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参考:
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[https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/arrow_functions](https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/arrow_functions)
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ブロックスコープは変数の有効範囲を制限します.(`if`文などの`{}`構文と同等.)
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```JavaScript
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const a = 1;
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{
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const a = 2
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console.log("inner", a);
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}
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console.log("outer", a);
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```
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参考:
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[https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Statements/block](https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Statements/block)
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