var test = '01234567890'; function split(t, ite) { var s = Date.now(); for (var j = 0; j < ite; j++) { var list = t.split(''); var str = ''; for (var i = 0, len = list.length; i < len; i++) { str += list[i]; } } console.log('with split(): ' + (Date.now() - s) + 'ms @ ' + ite); } function noSplit(t, ite) { var s = Date.now(); for (var j = 0; j < ite; j++) { var str = ''; for (var i = 0, len = t.length; i < len; i++) { str += t[i]; } } console.log('without split(): ' + (Date.now() - s) + 'ms @ ' + ite); } split(test, 100000); noSplit(test, 100000);