function smallestCommons(arr) { //return arr; var min = Math.min(arr[0],arr[1]); var max = Math.max(arr[0],arr[1]); var _arr = []; for(var i = min; i <= max; i++){ _arr.push(i); } var gcd = function(a,b){ if(b){ return gcd(b, a % b); } return a; }; return _arr.reduce(function(prev,cur,index,array){ return prev*cur/gcd(prev,cur); }); } smallestCommons([1,5]);