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49 lines
1020 B
49 lines
1020 B
4 years ago
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## Squared
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`.filter` is not the only useful array method that do loops for you.
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### `map`
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The `.map` method is another very powerful tool once mastered, let's see it in
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action:
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```js
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const time10 = [1, 2, 3, 4, 5].map((num) => {
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return `#${num}`
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})
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console.log(time10) // [`#1`, `#2`, `#3`, `#4`, `#5`]
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```
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Map takes a function and apply it to each elements of the array.
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Note that map will never change the number of element of the array
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For example if your function return nothing:
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```js
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const nothingX3 = [1, 2, 3].map((num) => {
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// Not doing anything today...
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})
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console.log(nothingX3) // [undefined, undefined, undefined]
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```
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We still get an array of 3 elements, but they are `undefined`.
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You should use map everytime you want to repeat the same action for all
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elements.
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### Instructions
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Declare a function `toSquares` that takes an array of numbers and return an
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array of those squared numbers
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**Example:**
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```js
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const result = toSquares([1, 2, 3, 4])
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console.log(result) // [1, 4, 9, 16]
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```
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