27 lines
1007 B
Markdown
27 lines
1007 B
Markdown
---
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title: initializeArrayWithRangeRight
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tags: array,intermediate
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firstSeen: 2018-01-16T17:09:39+02:00
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lastUpdated: 2020-10-20T23:02:01+03:00
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---
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Initializes an array containing the numbers in the specified range (in reverse) where `start` and `end` are inclusive with their common difference `step`.
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- Use `Array.from()` to create an array of the desired length, `(end - start + 1) / step`.
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- Use `Array.prototype.map()` to fill the array with the desired values in the given range.
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- Omit the second argument, `start`, to use a default value of `0`.
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- Omit the last argument, `step`, to use a default value of `1`.
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```js
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const initializeArrayWithRangeRight = (end, start = 0, step = 1) =>
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Array.from({ length: Math.ceil((end + 1 - start) / step) }).map(
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(v, i, arr) => (arr.length - i - 1) * step + start
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);
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```
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```js
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initializeArrayWithRangeRight(5); // [5, 4, 3, 2, 1, 0]
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initializeArrayWithRangeRight(7, 3); // [7, 6, 5, 4, 3]
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initializeArrayWithRangeRight(9, 0, 2); // [8, 6, 4, 2, 0]
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```
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