测试脚本运行时间

// 测试脚本运行时间
    var Timer = {
        _data : {},

        start : function(key){
            Timer._data[key] = new Date();
        },

        stop : function(key){
            var time = Timer._data[key];
            if(time){
                Timer._data[key] = new Date() - time;
            }
        },

        getTime : function(key){
            return Timer._data[key];
        }
    };

    var count = 10000, i,element;

    Timer.start('createElement');
    for(i = 0; i < count; i++){
        element = document.createElement("div");
    }

    Timer.stop('createElement');
    console.log('create' + count + 'in' + Timer.getTime('createElement'));