Check if an array contains any element of another array in JavaScript

Question

I have a target array [\"apple\",\"banana\",\"orange\"], and I want to check if other arrays contain any one of the target array elements.

For example:

Answer 1

Vanilla JS

ES2016:

const found = arr1.some(r=> arr2.includes(r))

ES6:

const found = arr1.some(r=> arr2.indexOf(r) >= 0)

How it works

some(..) checks each element of the array against a test function and returns true if any element of the array passes the test function, otherwise, it returns false. indexOf(..) >= 0 and includes(..) both return true if the given argument is present in the array.

Answer 2

If you're not opposed to using a libray, http://underscorejs.org/ has an intersection method, which can simplify this:

var _ = require('underscore');

var target = [ 'apple', 'orange', 'banana'];
var fruit2 = [ 'apple', 'orange', 'mango'];
var fruit3 = [ 'mango', 'lemon', 'pineapple'];
var fruit4 = [ 'orange', 'lemon', 'grapes'];

console.log(_.intersection(target, fruit2)); //returns [apple, orange]
console.log(_.intersection(target, fruit3)); //returns []
console.log(_.intersection(target, fruit4)); //returns [orange]

The intersection function will return a new array with the items that it matched and if not matches it returns empty array.