2018-10-10 22:03:03 +00:00
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---
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id: 587d7b88367417b2b2512b44
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2021-03-15 03:20:39 +00:00
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title: 编写带参数的箭头函数
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2018-10-10 22:03:03 +00:00
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challengeType: 1
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2020-08-04 07:13:35 +00:00
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forumTopicId: 301223
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2021-01-13 02:31:00 +00:00
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dashedName: write-arrow-functions-with-parameters
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2018-10-10 22:03:03 +00:00
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---
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2020-12-16 07:37:30 +00:00
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# --description--
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2021-03-15 03:20:39 +00:00
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和一般的函数一样,你也可以给箭头函数传递参数。
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2020-08-04 07:13:35 +00:00
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```js
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const doubler = (item) => item * 2;
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2021-03-15 03:20:39 +00:00
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doubler(4);
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2020-08-04 07:13:35 +00:00
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```
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2021-03-15 03:20:39 +00:00
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`doubler(4)` 将返回 `8`。
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如果箭头函数只有一个参数,则可以省略参数外面的括号。
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2020-08-04 07:13:35 +00:00
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```js
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const doubler = item => item * 2;
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```
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2021-03-15 03:20:39 +00:00
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可以给箭头函数传递多个参数。
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2020-08-04 07:13:35 +00:00
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```js
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const multiplier = (item, multi) => item * multi;
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2021-03-15 03:20:39 +00:00
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multiplier(4, 2);
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2020-08-04 07:13:35 +00:00
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```
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2021-03-15 03:20:39 +00:00
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`multiplier(4, 2)` 将返回 `8`。
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2020-12-16 07:37:30 +00:00
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# --instructions--
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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使用箭头函数的语法重写 `myConcat` 函数,将 `arr2` 的内容添加到 `arr1`。
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2020-12-16 07:37:30 +00:00
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# --hints--
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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应替换 `var` 关键词。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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(getUserInput) => assert(!getUserInput('index').match(/var/g));
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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`myConcat` 应该是一个常量(使用`const`)。
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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(getUserInput) => assert(getUserInput('index').match(/const\s+myConcat/g));
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2018-10-10 22:03:03 +00:00
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```
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2021-03-15 03:20:39 +00:00
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`myConcat` 应该是一个带有两个参数的箭头函数。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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2021-02-06 04:42:36 +00:00
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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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2020-12-16 07:37:30 +00:00
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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`myConcat()` 应该返回 `[1, 2, 3, 4, 5]`。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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2021-02-06 04:42:36 +00:00
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assert.deepEqual(myConcat([1, 2], [3, 4, 5]), [1, 2, 3, 4, 5]);
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2020-12-16 07:37:30 +00:00
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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不能使用 `function` 关键字。
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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(getUserInput) => assert(!getUserInput('index').match(/function/g));
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2018-10-10 22:03:03 +00:00
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```
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2020-08-04 07:13:35 +00:00
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2021-01-13 02:31:00 +00:00
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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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2020-12-16 07:37:30 +00:00
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# --solutions--
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2021-01-13 02:31:00 +00:00
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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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