jQuery选择器的性能测试(2)

                return this.ltLastTime = new Date().getTime(); 
            } 
            var diff = new Date().getTime() - this.ltLastTime; 
            this.ltLastTime = null; 
            $.l(diff); 
            return diff; 
        }, 
        ltLastTime: null 
    }); 
 
    /**
     * Shortcut function for benchmarking a block of code to the Firebug console
     * this function will run your code in a for block to create overflow and push the results into Firebug
     *
     * @param string benchmarkCode - the block of code you want to benchmark
     * @param numeric testTime - the number of FOR cicles
     */ 
    $.extend($, { 
        bm: function (benchmarkCode, testTime) { 
            this.testTime = typeof testTime === 'number' ? testTime : 9999; 
            $.lt(); 
            for (var i = 0;i < this.testTime;i++) { 
                eval(benchmarkCode); 
            } 
            $.lt(); 
        } 
    }); 
         
    /**
     * Mock ajax requests with a prefilter
     *
     */ 
    $.extend($, { 
        mockAjax: function (mockOptions) { 
            mockOptions = $.extend({ 
                mockUrl: '/ajax_mocks' 
            }, mockOptions); 
            $.ajaxPrefilter(function(options, originalOptions, jqXHR) {