freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/manipulate-arrays-with-unshift.md

id, challengeType, videoUrl, forumTopicId, title

id	challengeType	videoUrl	forumTopicId	title
56bbb991ad1ed5201cd392ce	1	https://scrimba.com/c/ckNDESv	18239	使用 unshift() 操作数组

Description

你不仅可以shift（移出）数组中的第一个元素，你也可以unshift（移入）一个元素到数组的头部。 .unshift()函数用起来就像.push()函数一样, 但不是在数组的末尾添加元素，而是在数组的头部添加元素。

Instructions

使用unshift()函数把["Paul",35]加入到myArray的头部。

Tests

tests:
  - text: <code>myArray</code>应该包含[["Paul", 35], ["dog", 3]]。
    testString: assert((function(d){if(typeof d[0] === "object" && d[0][0] == 'Paul' && d[0][1] === 35 && d[1][0] != undefined && d[1][0] == 'dog' && d[1][1] != undefined && d[1][1] == 3){return true;}else{return false;}})(myArray));

Challenge Seed

// Example
var ourArray = ["Stimpson", "J", "cat"];
ourArray.shift(); // ourArray now equals ["J", "cat"]
ourArray.unshift("Happy");
// ourArray now equals ["Happy", "J", "cat"]

// Setup
var myArray = [["John", 23], ["dog", 3]];
myArray.shift();

// Only change code below this line.

After Test

(function(y, z){return 'myArray = ' + JSON.stringify(y);})(myArray);

Solution

var myArray = [["John", 23], ["dog", 3]];
myArray.shift();
myArray.unshift(["Paul", 35]);