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