28 lines
827 B
Markdown
28 lines
827 B
Markdown
---
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title: Initialize mapped array
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type: snippet
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language: javascript
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tags: [array]
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author: chalarangelo
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cover: yellow-shoes
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dateModified: 2023-06-13T05:00:00-04:00
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---
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Initializes and fills an array with the specified values, using a mapping function.
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- Use the `Array()` constructor to create an array of the desired length.
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- Use `Array.prototype.fill()` to fill it with `null` values.
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- Use `Array.prototype.map()` to fill it with the desired values, using the provided function, `mapFn`.
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- Omit the second argument, `mapFn`, to map each element to its index.
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```js
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const initializeMappedArray = (n, mapFn = (_, i) => i) =>
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Array(n).fill(null).map(mapFn);
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```
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```js
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initializeMappedArray(5); // [0, 1, 2, 3, 4]
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initializeMappedArray(5, i => `item ${i + 1}`);
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// ['item 1', 'item 2', 'item 3', 'item 4', 'item 5']
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```
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