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

id, title, challengeType, videoUrl, forumTopicId

id	title	challengeType	videoUrl	forumTopicId
56bbb991ad1ed5201cd392ce	Manipulate Arrays With unshift()	1	https://scrimba.com/c/ckNDESv	18239

Description

Not only can you shift elements off of the beginning of an array, you can also unshift elements to the beginning of an array i.e. add elements in front of the array. .unshift() works exactly like .push(), but instead of adding the element at the end of the array, unshift() adds the element at the beginning of the array.

Example:

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

Instructions

Add ["Paul",35] to the beginning of the myArray variable using unshift().

Tests

tests:
  - text: <code>myArray</code> should now have [["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

// 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]);