132 lines
3.4 KiB
Markdown
132 lines
3.4 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244be
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title: Global Scope and Functions
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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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In JavaScript, <dfn>scope</dfn> refers to the visibility of variables. Variables which are defined outside of a function block have <dfn>Global</dfn> scope. This means, they can be seen everywhere in your JavaScript code.
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Variables which are used without the <code>var</code> keyword are automatically created in the <code>global</code> scope. This can create unintended consequences elsewhere in your code or when running a function again. You should always declare your variables with <code>var</code>.
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</section>
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## Instructions
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<section id='instructions'>
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Using <code>var</code>, declare a <code>global</code> variable <code>myGlobal</code> outside of any function. Initialize it with a value of <code>10</code>.
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Inside function <code>fun1</code>, assign <code>5</code> to <code>oopsGlobal</code> <strong><em>without</em></strong> using the <code>var</code> keyword.
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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: <code>myGlobal</code> should be defined
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testString: 'assert(typeof myGlobal != "undefined", "<code>myGlobal</code> should be defined");'
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- text: <code>myGlobal</code> should have a value of <code>10</code>
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testString: 'assert(myGlobal === 10, "<code>myGlobal</code> should have a value of <code>10</code>");'
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- text: <code>myGlobal</code> should be declared using the <code>var</code> keyword
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testString: 'assert(/var\s+myGlobal/.test(code), "<code>myGlobal</code> should be declared using the <code>var</code> keyword");'
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- text: <code>oopsGlobal</code> should be a global variable and have a value of <code>5</code>
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testString: 'assert(typeof oopsGlobal != "undefined" && oopsGlobal === 5, "<code>oopsGlobal</code> should be a global variable and have a value of <code>5</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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// Declare your variable here
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function fun1() {
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// Assign 5 to oopsGlobal Here
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}
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// Only change code above this line
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function fun2() {
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var output = "";
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if (typeof myGlobal != "undefined") {
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output += "myGlobal: " + myGlobal;
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}
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if (typeof oopsGlobal != "undefined") {
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output += " oopsGlobal: " + oopsGlobal;
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}
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console.log(output);
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}
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```
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</div>
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### Before Test
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<div id='js-setup'>
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```js
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var logOutput = "";
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var originalConsole = console
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function capture() {
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var nativeLog = console.log;
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console.log = function (message) {
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logOutput = message;
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if(nativeLog.apply) {
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nativeLog.apply(originalConsole, arguments);
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} else {
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var nativeMsg = Array.prototype.slice.apply(arguments).join(' ');
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nativeLog(nativeMsg);
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}
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};
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}
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function uncapture() {
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console.log = originalConsole.log;
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}
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var oopsGlobal;
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capture();
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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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// Declare your variable here
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var myGlobal = 10;
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function fun1() {
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// Assign 5 to oopsGlobal Here
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oopsGlobal = 5;
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}
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// Only change code above this line
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function fun2() {
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var output = "";
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if(typeof myGlobal != "undefined") {
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output += "myGlobal: " + myGlobal;
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}
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if(typeof oopsGlobal != "undefined") {
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output += " oopsGlobal: " + oopsGlobal;
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}
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console.log(output);
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}
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```
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</section>
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