I believe this wouldn't result in the OP's desired results since the
filtered array is no longer the same length as the original array:
```js
var toggle = (arr, el) => Object.assign(arr, arr.filter(n => n !== el));
toggle([1, 2, 3, 2, 1], 1); // [2, 3 ,2, 2, 1]
```
Here's a helper function that would work (and also push the element if it's
not included in the original array):
```js
var toggle = (arr, el) => {
var len = arr.length;
for (var i = 0; i < arr.length; i++)
if (arr[i] === el)
arr.splice(i--, 1);
if (arr.length === len)
arr.push(el);
return arr;
};
var a = toggle([1, 2, 3, 2, 1], 1); // mutates the original array removing
1 => [2, 3, 2]
toggle(a, 1); // mutates the original array adding 1 => [2, 3, 2, 1]
```
On Fri, Feb 7, 2020 at 11:26 AM Herby Vojčík <[email protected]> wrote:
> On 7. 2. 2020 13:11, Scott Rudiger wrote:
> > `Array.prototype.filter` seems more versatile (although it doesn't
> > mutate the original array) since it removes elements based on a function:
> >
> > ```js
> > [1, 2, 3, 2, 1].filter(n => n !== 1); // [2, 3, 2]
> > ```
>
> But what if one wants to mutate in-place. Would this work?
>
> Object.assign(arr, arr.filter(n => n !== 1))
>
> If not, maybe there can be
>
> aCollection.replaceWith(anIterable)
>
> Herby
>
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