bd68b70f3d
* fix: remove isHidden flag from frontmatter * fix: add isUpcomingChange Co-authored-by: Ahmad Abdolsaheb <ahmad.abdolsaheb@gmail.com> * feat: hide blocks not challenges Co-authored-by: Ahmad Abdolsaheb <ahmad.abdolsaheb@gmail.com> Co-authored-by: Ahmad Abdolsaheb <ahmad.abdolsaheb@gmail.com>
76 lines
2.5 KiB
Markdown
76 lines
2.5 KiB
Markdown
---
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id: bd7123c9c443eddfaeb5bdef
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title: Declare JavaScript Variables
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/cNanrHq'
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forumTopicId: 17556
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---
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## Description
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<section id='description'>
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In computer science, <dfn>data</dfn> is anything that is meaningful to the computer. JavaScript provides eight different <dfn>data types</dfn> which are <code>undefined</code>, <code>null</code>, <code>boolean</code>, <code>string</code>, <code>symbol</code>, <code>bigint</code>, <code>number</code>, and <code>object</code>.
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For example, computers distinguish between numbers, such as the number <code>12</code>, and <code>strings</code>, such as <code>"12"</code>, <code>"dog"</code>, or <code>"123 cats"</code>, which are collections of characters. Computers can perform mathematical operations on a number, but not on a string.
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<dfn>Variables</dfn> allow computers to store and manipulate data in a dynamic fashion. They do this by using a "label" to point to the data rather than using the data itself. Any of the eight data types may be stored in a variable.
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<code>Variables</code> are similar to the x and y variables you use in mathematics, which means they're a simple name to represent the data we want to refer to. Computer <code>variables</code> differ from mathematical variables in that they can store different values at different times.
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We tell JavaScript to create or <dfn>declare</dfn> a variable by putting the keyword <code>var</code> in front of it, like so:
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```js
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var ourName;
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```
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creates a <code>variable</code> called <code>ourName</code>. In JavaScript we end statements with semicolons.
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<code>Variable</code> names can be made up of numbers, letters, and <code>$</code> or <code>_</code>, but may not contain spaces or start with a number.
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</section>
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## Instructions
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<section id='instructions'>
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Use the <code>var</code> keyword to create a variable called <code>myName</code>.
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<strong>Hint</strong><br>Look at the <code>ourName</code> example above if you get stuck.
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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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tests:
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- text: You should declare <code>myName</code> with the <code>var</code> keyword, ending with a semicolon
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testString: assert(/var\s+myName\s*;/.test(code));
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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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```
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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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if(typeof myName !== "undefined"){(function(v){return v;})(myName);}
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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 myName;
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```
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</section>
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