Loop is more important than rest?

Question

I want to execute simple code when user click on my button:

1. First: change my cursor to \'wait\'
2. Next: execute loop
3. When loop is finished: cha

Answer 1

RequestAnimationFrame Way

jsFiddle here

(function (W) {
    W.onload = function () {
        var D = W.document,
            a = 0,
            c = D.getElementById('progress');

        function b() {
            c.innerText = a + 1;
            a++;
            if (a < 500) {
                requestAnimationFrame(b);
            } else {
                D.body.style.cursor = 'default';
            }
        }

        function start() {
            D.body.style.cursor = 'wait';
            b()
        }
        D.getElementById('gogogo').onclick = start;
    }
})(window)

This way you use less resources and so your complex link modification does not slow down other open websites.