How to check if all array elements are equal to a given value in JavaScript

In this Article we will go through how to check if all array elements are equal to a given value only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const isEqual = (arr, value) => arr.every(item => item === value);

// Ends earlier for false arrays
const isEqual = (arr, value) => !arr.some(item => item !== value);

isEqual(['foo', 'foo'], 'foo');     // true
isEqual(['foo', 'bar'], 'foo');     // false
isEqual(['bar', 'bar'], 'foo');     // false