27 lines
759 B
Markdown
27 lines
759 B
Markdown
---
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title: Drop list elements from the right based on function
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tags: array
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expertise: intermediate
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cover: blog_images/bridge-drop.jpg
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firstSeen: 2018-01-26T12:23:18+02:00
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lastUpdated: 2020-10-19T18:51:03+03:00
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---
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Removes elements from the end of an array until the passed function returns `true`.
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Returns the remaining elements in the array.
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- Loop through the array, using `Array.prototype.slice()` to drop the last element of the array until the value returned from `func` is `true`.
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- Return the remaining elements.
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```js
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const dropRightWhile = (arr, func) => {
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let rightIndex = arr.length;
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while (rightIndex-- && !func(arr[rightIndex]));
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return arr.slice(0, rightIndex + 1);
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};
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```
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```js
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dropRightWhile([1, 2, 3, 4], n => n < 3); // [1, 2]
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```
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