95 lines
1.7 KiB
Markdown
95 lines
1.7 KiB
Markdown
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---
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id: 587d7b88367417b2b2512b44
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title: 編寫帶參數的箭頭函數
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challengeType: 1
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forumTopicId: 301223
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dashedName: write-arrow-functions-with-parameters
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---
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# --description--
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和一般的函數一樣，你也可以給箭頭函數傳遞參數。
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```js
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const doubler = (item) => item * 2;
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doubler(4);
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```
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`doubler(4)` 將返回 `8`。
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如果箭頭函數只有一個參數，則可以省略參數外面的括號。
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```js
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const doubler = item => item * 2;
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```
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可以給箭頭函數傳遞多個參數。
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```js
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const multiplier = (item, multi) => item * multi;
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multiplier(4, 2);
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```
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`multiplier(4, 2)` 將返回 `8`。
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# --instructions--
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使用箭頭函數的語法重寫 `myConcat` 函數，將 `arr2` 的內容添加到 `arr1`。
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# --hints--
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應替換 `var` 關鍵詞。
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```js
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(getUserInput) => assert(!getUserInput('index').match(/var/g));
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```
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`myConcat` 應該是一個常量（使用`const`）。
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```js
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(getUserInput) => assert(getUserInput('index').match(/const\s+myConcat/g));
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```
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`myConcat` 應該是一個帶有兩個參數的箭頭函數。
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```js
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assert(
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/myConcat=\(\w+,\w+\)=>/.test(code.replace(/\s/g, '')) &&
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typeof myConcat === 'function'
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);
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```
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`myConcat()` 應該返回 `[1, 2, 3, 4, 5]`。
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```js
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assert.deepEqual(myConcat([1, 2], [3, 4, 5]), [1, 2, 3, 4, 5]);
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```
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不能使用 `function` 關鍵字。
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```js
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(getUserInput) => assert(!getUserInput('index').match(/function/g));
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```
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# --seed--
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## --seed-contents--
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```js
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var myConcat = function(arr1, arr2) {
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return arr1.concat(arr2);
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};
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console.log(myConcat([1, 2], [3, 4, 5]));
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```
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# --solutions--
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```js
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const myConcat = (arr1, arr2) => {
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return arr1.concat(arr2);
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};
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console.log(myConcat([1, 2], [3, 4, 5]));
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```
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