javascript assert all same in list 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: every element in list after first javascript

var middlePoints = ['A', 'B', 'C', 'D'];
middlePoints.shift();

console.log(middlePoints); //['B', 'C', 'D']