Sum square difference

eular_6.js

function result() {
    var i = 0;
    var i2 = 0;
    for (var z = 1; z <= 100; z++) {
        i += z;
        i2 += Math.pow(z, 2);
    }
    return Math.pow(i, 2) - i2;
}

document.write(result());