28 lines
926 B
Markdown
28 lines
926 B
Markdown
---
|
|
title: Remove list elements from the end while condition is met
|
|
type: snippet
|
|
tags: [array]
|
|
cover: beach-pineapple
|
|
dateModified: 2020-11-29T12:04:53+02:00
|
|
---
|
|
|
|
Removes elements from the end of an array until the passed function returns `false`.
|
|
Returns the removed elements.
|
|
|
|
- Create a reversed copy of the array, using the spread operator (`...`) and `Array.prototype.reverse()`.
|
|
- Loop through the reversed copy, using a `for...of` loop over `Array.prototype.entries()` until the returned value from the function is falsy.
|
|
- Return the removed elements, using `Array.prototype.slice()`.
|
|
- The callback function, `fn`, accepts a single argument which is the value of the element.
|
|
|
|
```js
|
|
const takeRightWhile = (arr, fn) => {
|
|
for (const [i, val] of [...arr].reverse().entries())
|
|
if (!fn(val)) return i === 0 ? [] : arr.slice(-i);
|
|
return arr;
|
|
};
|
|
```
|
|
|
|
```js
|
|
takeRightWhile([1, 2, 3, 4], n => n >= 3); // [3, 4]
|
|
```
|