freeCodeCamp/use-destructuring-assignment-with-the-rest-parameter-to-reassign-array-elements.chinese.md at c40eab94b7748a5aa0de26bd008883773a4f5ab4

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ZhichengChen 83957bb150 fix(i18n): update Chinese translation of es6 (#38038 )

Co-authored-by: Zhicheng Chen <chenzhicheng@dayuwuxian.com>

2020-08-04 12:43:35 +05:30

2.4 KiB

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id, title, challengeType, forumTopicId, localeTitle

id	title	challengeType	forumTopicId	localeTitle
587d7b8a367417b2b2512b4c	Use Destructuring Assignment with the Rest Parameter to Reassign Array Elements	1	301218	使用解构赋值配合 rest 操作符来重新分配数组元素

Description

在解构数组的某些情况下，我们可能希望将剩下的元素放进另一个数组里面。以下代码的结果与使用Array.prototype.slice()相同：

const [a, b, ...arr] = [1, 2, 3, 4, 5, 7];
console.log(a, b); // 1, 2
console.log(arr); // [3, 4, 5, 7]

变量a与b分别获取了数组的前两个元素的值。之后，因为rest操作符的存在，arr获取了原数组剩余的元素的值，并构成了一个新的数组。 rest操作只能对数组列表最后的元素起作用。这意味着你不能使用rest操作符来截取原数组中间元素的子数组。

Instructions

使用解构赋值以及rest操作符来进行一个Array.prototype.slice相同的操作。使得arr是原数组source除开前两个元素的子数组。

Tests

tests:
  - text: <code>arr</code>应该为<code>[3,4,5,6,7,8,9,10]</code>
    testString: assert(arr.every((v, i) => v === i + 3) && arr.length === 8);
  - text: 没有使用<code>Array.slice()</code>。
    testString: getUserInput => assert(!getUserInput('index').match(/slice/g));
  - text: 使用了解构赋值。
    testString: assert(code.replace(/\s/g, '').match(/\[(([_$a-z]\w*)?,){1,}\.\.\.arr\]=list/i));

Challenge Seed

const source = [1,2,3,4,5,6,7,8,9,10];
function removeFirstTwo(list) {
  "use strict";
  // change code below this line
  const arr = list; // change this
  // change code above this line
  return arr;
}
const arr = removeFirstTwo(source);
console.log(arr); // should be [3,4,5,6,7,8,9,10]
console.log(source); // should be [1,2,3,4,5,6,7,8,9,10];

Solution

const source = [1,2,3,4,5,6,7,8,9,10];
function removeFirstTwo(list) {
  "use strict";
  // change code below this line
  const [, , ...arr] = list;
  // change code above this line
  return arr;
}
const arr = removeFirstTwo(source);

2.4 KiB Raw Blame History