/** * Given an array of number, group algebraic sequences with d=1 * [1,2,3,4,5,6] => true * [1,2,4,5,6] => false */ var arr = [1,2,4,5,6]; const differenceAry = arr.slice(1).map(function(n, i) { return n - arr[i]; }) const isDifference= differenceAry.every(value => value == 1) console.log(isDifference); // False