93 lines
2.4 KiB
Markdown
93 lines
2.4 KiB
Markdown
---
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id: 5675e877dbd60be8ad28edc6
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title: Iterate Through an Array with a For Loop
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challengeType: 1
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---
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## Description
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<section id='description'>
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A common task in JavaScript is to iterate through the contents of an array. One way to do that is with a <code>for</code> loop. This code will output each element of the array <code>arr</code> to the console:
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<blockquote>var arr = [10,9,8,7,6];<br>for (var i = 0; i < arr.length; i++) {<br> console.log(arr[i]);<br>}</blockquote>
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Remember that Arrays have zero-based numbering, which means the last index of the array is length - 1. Our <dfn>condition</dfn> for this loop is <code>i < arr.length</code>, which stops when <code>i</code> is at length - 1.
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</section>
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## Instructions
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<section id='instructions'>
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Declare and initialize a variable <code>total</code> to <code>0</code>. Use a <code>for</code> loop to add the value of each element of the <code>myArr</code> array to <code>total</code>.
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</section>
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## Tests
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<section id='tests'>
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```yml
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- text: <code>total</code> should be declared and initialized to 0
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testString: 'assert(code.match(/var.*?total\s*=\s*0.*?;/), "<code>total</code> should be declared and initialized to 0");'
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- text: <code>total</code> should equal 20
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testString: 'assert(total === 20, "<code>total</code> should equal 20");'
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- text: You should use a <code>for</code> loop to iterate through <code>myArr</code>
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testString: 'assert(code.match(/for\s*\(/g).length > 1 && code.match(/myArr\s*\[/), "You should use a <code>for</code> loop to iterate through <code>myArr</code>");'
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- text: Do not set <code>total</code> to 20 directly
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testString: 'assert(!code.match(/total[\s\+\-]*=\s*(\d(?!\s*[;,])|[1-9])/g), "Do not set <code>total</code> to 20 directly");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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// Example
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var ourArr = [ 9, 10, 11, 12];
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var ourTotal = 0;
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for (var i = 0; i < ourArr.length; i++) {
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ourTotal += ourArr[i];
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}
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// Setup
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var myArr = [ 2, 3, 4, 5, 6];
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// Only change code below this line
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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console.info('after the test');
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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var ourArr = [ 9, 10, 11, 12];
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var ourTotal = 0;
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for (var i = 0; i < ourArr.length; i++) {
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ourTotal += ourArr[i];
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}
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var myArr = [ 2, 3, 4, 5, 6];
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var total = 0;
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for (var i = 0; i < myArr.length; i++) {
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total += myArr[i];
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}
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```
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</section>
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