var test = []; for( var i = 0; i < 10000; i++ ){ test.push(i); } function sum(test,initial){ initial = initial || 0; return test.length===0?initial:initial + test.shift() + sum(test); } function sumTCO(test,initial){ initial = initial || 0; return test.length===0?initial:sumTCO( test, initial+test.shift()); } //console.log(sum(test)); console.log(sumTCO(test));