Throttle JavaScript function calls, but with queuing (don't discard calls)

Question

How can a function rate-limit its calls? The calls should not be discarded if too frequent, but rather be queued up and spaced out in time, X milliseconds apart. I\'ve looked at

Answer 1

Should be rather simple without a library:

var stack = [], 
    timer = null;

function process() {
    var item = stack.shift();
    // process
    if (stack.length === 0) {
        clearInterval(timer);
        timer = null;
    }
}

function queue(item) {
    stack.push(item);
    if (timer === null) {
        timer = setInterval(process, 500);
    }
}

http://jsfiddle.net/6TPed/4/