if element is equal to any element of an array javascript code example

Example 1: check if array has same values javascript

const allEqual = arr => arr.every(v => v === arr[0]);
allEqual([1,1,1,1]);  // true

Example 2: check array values equal js

[1,1,1,1].every( (val, i, arr) => val === arr[0] )   // true