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30-seconds-of-code/snippets/takeWhile.md
Mathias Bynens 8ee50178f3 Avoid confusing prototype methods for static methods
Correct: `Array.from()` (it’s a static method)
Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method)

This patch uses the common `#` syntax to denote `.prototype.`.
2018-09-28 15:44:12 -04:00

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Markdown

### takeWhile
Removes elements in an array until the passed function returns `true`. Returns the removed elements.
Loop through the array, using a `for...of` loop over `Array.prototype.entries()` until the returned value from the function is `true`.
Return the removed elements, using `Array.prototype.slice()`.
```js
const takeWhile = (arr, func) => {
for (const [i, val] of arr.entries()) if (func(val)) return arr.slice(0, i);
return arr;
};
```
```js
takeWhile([1, 2, 3, 4], n => n >= 3); // [1, 2]
```