freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-an.../basic-javascript/access-array-data-with-inde...

84 lines
2.3 KiB
Markdown
Raw Normal View History

---
id: 56bbb991ad1ed5201cd392ca
title: Access Array Data with Indexes
challengeType: 1
videoUrl: 'https://scrimba.com/c/cBZQbTz'
---
## Description
<section id='description'>
We can access the data inside arrays using <code>indexes</code>.
Array indexes are written in the same bracket notation that strings use, except that instead of specifying a character, they are specifying an entry in the array. Like strings, arrays use <dfn>zero-based</dfn> indexing, so the first element in an array is element <code>0</code>.
<br />
<strong>Example</strong>
```js
var array = [50,60,70];
array[0]; // equals 50
var data = array[1]; // equals 60
```
<strong>Note</strong><br>There shouldn't be any spaces between the array name and the square brackets, like <code>array [0]</code>. Although JavaScript is able to process this correctly, this may confuse other programmers reading your code.
</section>
## Instructions
<section id='instructions'>
Create a variable called <code>myData</code> and set it to equal the first value of <code>myArray</code> using bracket notation.
</section>
## Tests
<section id='tests'>
```yml
tests:
- text: The variable <code>myData</code> should equal the first value of <code>myArray</code>.
testString: assert((function(){if(typeof myArray !== 'undefined' && typeof myData !== 'undefined' && myArray[0] === myData){return true;}else{return false;}})(), 'The variable <code>myData</code> should equal the first value of <code>myArray</code>.');
- text: The data in variable <code>myArray</code> should be accessed using bracket notation.
testString: assert((function(){if(code.match(/\s*=\s*myArray\[0\]/g)){return true;}else{return false;}})(), 'The data in variable <code>myArray</code> should be accessed using bracket notation.');
```
</section>
## Challenge Seed
<section id='challengeSeed'>
<div id='js-seed'>
```js
// Example
var ourArray = [50,60,70];
var ourData = ourArray[0]; // equals 50
// Setup
var myArray = [50,60,70];
// Only change code below this line.
```
</div>
### After Test
<div id='js-teardown'>
```js
if(typeof myArray !== "undefined" && typeof myData !== "undefined"){(function(y,z){return 'myArray = ' + JSON.stringify(y) + ', myData = ' + JSON.stringify(z);})(myArray, myData);}
```
</div>
</section>
## Solution
<section id='solution'>
```js
var myArray = [50,60,70];
var myData = myArray[0];
```
</section>