29 lines
695 B
Markdown
29 lines
695 B
Markdown
---
|
|
title: Array union based on function
|
|
type: snippet
|
|
language: javascript
|
|
tags: [array]
|
|
cover: orange-coffee-4
|
|
dateModified: 2020-10-22T20:24:44+03:00
|
|
---
|
|
|
|
Returns every element that exists in any of the two arrays at least once, using a provided comparator function.
|
|
|
|
- Create a `Set` with all values of `a` and values in `b` for which the comparator finds no matches in `a`, using `Array.prototype.findIndex()`.
|
|
|
|
```js
|
|
const unionWith = (a, b, comp) =>
|
|
Array.from(
|
|
new Set([...a, ...b.filter(x => a.findIndex(y => comp(x, y)) === -1)])
|
|
);
|
|
```
|
|
|
|
```js
|
|
unionWith(
|
|
[1, 1.2, 1.5, 3, 0],
|
|
[1.9, 3, 0, 3.9],
|
|
(a, b) => Math.round(a) === Math.round(b)
|
|
);
|
|
// [1, 1.2, 1.5, 3, 0, 3.9]
|
|
```
|