99 lines
1.9 KiB
Markdown
99 lines
1.9 KiB
Markdown
---
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id: 587d7b8b367417b2b2512b50
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title: Write Concise Declarative Functions with ES6
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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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When defining functions within objects in ES5, we have to use the keyword <code>function</code> as follows:
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```js
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const person = {
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name: "Taylor",
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sayHello: function() {
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return `Hello! My name is ${this.name}.`;
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}
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};
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```
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With ES6, You can remove the <code>function</code> keyword and colon altogether when defining functions in objects. Here's an example of this syntax:
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```js
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const person = {
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name: "Taylor",
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sayHello() {
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return `Hello! My name is ${this.name}.`;
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}
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};
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```
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</section>
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## Instructions
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<section id='instructions'>
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Refactor the function <code>setGear</code> inside the object <code>bicycle</code> to use the shorthand syntax described above.
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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: Traditional function expression should not be used.
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testString: getUserInput => assert(!removeJSComments(code).match(/function/));
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- text: <code>setGear</code> should be a declarative function.
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testString: assert(typeof bicycle.setGear === 'function' && code.match(/setGear\s*\(.+\)\s*\{/));
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- text: <code>bicycle.setGear(48)</code> should change the <code>gear</code> value to 48.
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testString: assert((new bicycle.setGear(48)).gear === 48);
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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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// change code below this line
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const bicycle = {
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gear: 2,
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setGear: function(newGear) {
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this.gear = newGear;
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}
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};
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// change code above this line
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bicycle.setGear(3);
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console.log(bicycle.gear);
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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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const removeJSComments = str => str.replace(/\/\*[\s\S]*?\*\/|\/\/.*$/gm, '');
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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 bicycle = {
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gear: 2,
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setGear(newGear) {
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this.gear = newGear;
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}
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};
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bicycle.setGear(3);
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```
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</section>
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