80 lines
3.4 KiB
Markdown
80 lines
3.4 KiB
Markdown
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---
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id: 587d7db2367417b2b2512b8c
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title: Use an IIFE to Create a Module
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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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An <code>immediately invoked function expression</code> (<code>IIFE</code>) is often used to group related functionality into a single object or <code>module</code>. For example, an earlier challenge defined two mixins:
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<blockquote>function glideMixin(obj) {<br> obj.glide = function() {<br> console.log("Gliding on the water");<br> };<br>}<br>function flyMixin(obj) {<br> obj.fly = function() {<br> console.log("Flying, wooosh!");<br> };<br>}</blockquote>
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We can group these <code>mixins</code> into a module as follows:
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<blockquote>let motionModule = (function () {<br> return {<br> glideMixin: function (obj) {<br> obj.glide = function() {<br> console.log("Gliding on the water");<br> };<br> },<br> flyMixin: function(obj) {<br> obj.fly = function() {<br> console.log("Flying, wooosh!");<br> };<br> }<br> }<br>}) (); // The two parentheses cause the function to be immediately invoked</blockquote>
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Note that you have an <code>immediately invoked function expression</code> (<code>IIFE</code>) that returns an object <code>motionModule</code>. This returned object contains all of the <code>mixin</code> behaviors as properties of the object.
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The advantage of the <code>module</code> pattern is that all of the motion behaviors can be packaged into a single object that can then be used by other parts of your code. Here is an example using it:
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<blockquote>motionModule.glideMixin(duck);<br>duck.glide();</blockquote>
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</section>
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## Instructions
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<section id='instructions'>
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Create a <code>module</code> named <code>funModule</code> to wrap the two <code>mixins</code> <code>isCuteMixin</code> and <code>singMixin</code>. <code>funModule</code> should return an object.
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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>funModule</code> should be defined and return an object.
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testString: 'assert(typeof funModule === "object", "<code>funModule</code> should be defined and return an object.");'
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- text: <code>funModule.isCuteMixin</code> should access a function.
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testString: 'assert(typeof funModule.isCuteMixin === "function", "<code>funModule.isCuteMixin</code> should access a function.");'
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- text: <code>funModule.singMixin</code> should access a function.
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testString: 'assert(typeof funModule.singMixin === "function", "<code>funModule.singMixin</code> should access a function.");'
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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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let isCuteMixin = function(obj) {
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obj.isCute = function() {
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return true;
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};
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};
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let singMixin = function(obj) {
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obj.sing = function() {
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console.log("Singing to an awesome tune");
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};
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};
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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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const funModule = (function () {
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return {
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isCuteMixin: obj => {
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obj.isCute = () => true;
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},
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singMixin: obj => {
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obj.sing = () => console.log("Singing to an awesome tune");
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}
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};
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})();
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```
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</section>
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