【性能】web提升性能的小总结

            if (typeof echarts === ‘undefined‘) {
                console.log(‘异步加载echarts‘);
                $.getScript(_relyScripts, function () {
                    _this.showWhLatencyData();
                });                
            }else {
                console.log(‘已加载echarts‘);
                _this.showWhLatencyData();
            }