A custom debouncing function

debounce.js

// Returns a function that can't be called more than once per `delay`,
// with a maximum delay of `maxDelay`. The returned function can be called
// forcefully through its `flush` property
function debounce(fn, delay, maxDelay) {
    var timer;
    var maxTimer;
    var args;

    var clearTimers = function () {
        if (timer) clearTimeout(timer);
        if (maxTimer) clearTimeout(maxTimer);
    };

    var doCallFn = function () {
        clearTimers();
        fn.apply(undefined, [].slice(args));
    };

    var debounced = function () {
        args = arguments;
        // Reset the timer
        if (timer) {
            clearTimeout(timer);
        }
        timer = setTimeout(doCallFn, delay);

        if (!maxTimer) {
            maxTimer = setTimeout(doCallFn, maxDelay);
        }
    };

    // Forces a call
    debounced.flush = doCallFn;

    return debounced;
}