回答編集履歴
2
スコープを調整
test
CHANGED
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@@ -14,13 +14,29 @@
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'use strict';
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-
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function eachfn (asset) {
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-
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console.log(this, asset);
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}
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function main () {
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var assets = [1,2,3,4,5];
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var trustId = 'trust';
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assets.forEach(
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assets.forEach(eachfn, trustId);
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}
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main();
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```
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@@ -42,13 +58,29 @@
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'use strict';
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function eachfn (trustId, asset) {
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console.log(trustId, asset);
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}
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function main () {
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var assets = [1,2,3,4,5];
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var trustId = 'trust';
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assets.forEach(f
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assets.forEach(eachfn.bind(undefined, trustId));
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}
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main();
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```
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1
Function.prototype.bind
test
CHANGED
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@@ -1,4 +1,56 @@
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1
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### Array.prototype.forEach()
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1
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第二引数でthis値
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`Array.prototype.forEach` の第二引数で `this` 値を束縛可能です。
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- [Array.prototype.forEach() - JavaScript | MDN](https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach#parameters)
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```JavaScript
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'use strict';
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var assets = [1,2,3,4,5];
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var trustId = 'trust';
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assets.forEach(function (asset) { console.log(this); }, trustId);
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```
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### Function.prototype.bind()
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`Function.prototype.bind` で引数を束縛可能です。
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- [Function.prototype.bind() - JavaScript | MDN](https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Function/bind)
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```JavaScript
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'use strict';
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var assets = [1,2,3,4,5];
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var trustId = 'trust';
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assets.forEach(function (trustId, asset) { console.log(trustId, asset); }.bind(null, trustId));
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```
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