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

id, title, challengeType, videoUrl, forumTopicId

id	title	challengeType	videoUrl	forumTopicId
56bbb991ad1ed5201cd392cd	Manipulate Arrays With shift()	1	https://scrimba.com/c/cRbVETW	18238

Description

pop() always removes the last element of an array. What if you want to remove the first? That's where .shift() comes in. It works just like .pop(), except it removes the first element instead of the last.

Example:

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

Instructions

Use the .shift() function to remove the first item from myArray, assigning the "shifted off" value to removedFromMyArray.

Tests

tests:
  - text: <code>myArray</code> should now equal <code>[["dog", 3]]</code>.
    testString: assert((function(d){if(d[0][0] == 'dog' && d[0][1] === 3 && d[1] == undefined){return true;}else{return false;}})(myArray));
  - text: <code>removedFromMyArray</code> should contain <code>["John", 23]</code>.
    testString: assert((function(d){if(d[0] == 'John' && d[1] === 23 && typeof removedFromMyArray === 'object'){return true;}else{return false;}})(removedFromMyArray));

Challenge Seed

// Setup
var myArray = [["John", 23], ["dog", 3]];

// Only change code below this line
var removedFromMyArray;

After Test

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

Solution

var myArray = [["John", 23], ["dog", 3]];

// Only change code below this line
var removedFromMyArray = myArray.shift();