95 lines
1.8 KiB
Markdown
95 lines
1.8 KiB
Markdown
---
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id: 587d7b88367417b2b2512b44
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title: Write Arrow Functions with Parameters
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challengeType: 1
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forumTopicId: 301223
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dashedName: write-arrow-functions-with-parameters
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---
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# --description--
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Just like a regular function, you can pass arguments into an arrow function.
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```js
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const doubler = (item) => item * 2;
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doubler(4);
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```
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`doubler(4)` would return the value `8`.
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If an arrow function has a single parameter, the parentheses enclosing the parameter may be omitted.
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```js
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const doubler = item => item * 2;
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```
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It is possible to pass more than one argument into an arrow function.
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```js
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const multiplier = (item, multi) => item * multi;
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multiplier(4, 2);
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```
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`multiplier(4, 2)` would return the value `8`.
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# --instructions--
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Rewrite the `myConcat` function which appends contents of `arr2` to `arr1` so that the function uses arrow function syntax.
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# --hints--
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You should replace the `var` keyword.
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```js
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(getUserInput) => assert(!getUserInput('index').match(/var/g));
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```
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`myConcat` should be a constant variable (by using `const`).
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```js
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(getUserInput) => assert(getUserInput('index').match(/const\s+myConcat/g));
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```
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`myConcat` should be an arrow function with two parameters
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```js
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assert(
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/myConcat=\(\w+,\w+\)=>/.test(code.replace(/\s/g, '')) &&
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typeof myConcat === 'function'
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);
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```
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`myConcat()` should return `[1, 2, 3, 4, 5]`.
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```js
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assert.deepEqual(myConcat([1, 2], [3, 4, 5]), [1, 2, 3, 4, 5]);
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```
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The `function` keyword should not be used.
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```js
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(getUserInput) => assert(!getUserInput('index').match(/function/g));
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```
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# --seed--
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## --seed-contents--
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```js
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var myConcat = function(arr1, arr2) {
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return arr1.concat(arr2);
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};
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console.log(myConcat([1, 2], [3, 4, 5]));
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```
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# --solutions--
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```js
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const myConcat = (arr1, arr2) => {
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return arr1.concat(arr2);
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};
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console.log(myConcat([1, 2], [3, 4, 5]));
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```
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