var arr = ['a', 'b', 'c', 'd', 'e', 'f','g','h','i','a','b','c','d','r','f','c','e','y','r']; var result = []; var idx = 0; console.log(arr.slice(0,3)) for (var i = 0 ; i< arr.length; i += 3){ if(i == 0){ result[idx] = arr.slice(0,3); } else if (i + 3 > arr.length){ result[idx] = arr.slice(i) } else{ result[idx] = arr.slice(i,i+3) } idx += 1; } // var indexToSplit = arr.indexOf('c'); // var first = arr.slice(0, indexToSplit); // var second = arr.slice(indexToSplit + 1); console.log(result);