javascript 防止重复点击

    var debounce = function (func, wait, lossless) {
        var lastTimeout, alreadyDo = false;
        if (typeof lossless == 'undefined')
            lossless = true;
        return function () {
            var context = this,
                  args = arguments;
            if (!alreadyDo) {
                alreadyDo = true;
                setTimeout(function () { alreadyDo = false }, wait);
                clearTimeout(lastTimeout);
                func.apply(context, args);
            } else if (lossless) {
                clearTimeout(lastTimeout);
                lastTimeout = setTimeout(function () {
                    func.apply(context, args);
                }, wait);
            }
        };
    }