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30-seconds-of-code/snippets/js/s/function-based-array-intersection.md
Angelos Chalaris 9d032ce05e Rename js snippets
2023-05-19 20:23:47 +03:00

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---
title: Array intersection based on function
type: snippet
language: javascript
tags: [array]
cover: digital-nomad-2
dateModified: 2020-10-20T23:02:01+03:00
---
Returns the elements that exist in both arrays, using a provided comparator function.
- Use `Array.prototype.filter()` and `Array.prototype.findIndex()` in combination with the provided comparator to determine intersecting values.
```js
const intersectionWith = (a, b, comp) =>
a.filter(x => b.findIndex(y => comp(x, y)) !== -1);
```
```js
intersectionWith(
[1, 1.2, 1.5, 3, 0],
[1.9, 3, 0, 3.9],
(a, b) => Math.round(a) === Math.round(b)
); // [1.5, 3, 0]
```