Better Y.throttle()

gistfile1.js

// New Y.throttle().
Y.throttle = function (fn, duration, context) {
    var lastTime = 0,
        lastArgs, timeout;

    duration || (duration = Y.config.throttleTime || 150);

    function execute() {
        var args = lastArgs;

        lastArgs = null;
        lastTime = Y.Lang.now();
        timeout  = null;

        fn.apply(context, args);
    }

    return function () {
        var now;

        lastArgs = arguments;

        if (timeout) { return; }

        now = Y.Lang.now();

        if (now - lastTime > duration) {
            lastArgs = null;
            lastTime = now;

            fn.apply(context, arguments);
        } else {
            timeout = setTimeout(execute, duration);
        }
    };
};

// Old Y.throttle().
Y.throttle = function(fn, ms) {
    ms = (ms) ? ms : (Y.config.throttleTime || 150);

    if (ms === -1) {
        return (function() {
            fn.apply(null, arguments);
        });
    }

    var last = Y.Lang.now();

    return (function() {
        var now = Y.Lang.now();
        if (now - last > ms) {
            last = now;
            fn.apply(null, arguments);
        }
    });
};