         var chart = echarts.init(document.getElementById('main'), null, {
                    renderer: 'canvas'
                });

                chart.showLoading({
                    text : '正在读取数据中...'
                });

                var xAxisData = [];
                var data1 = [];
                var data2 = [];
                var data3 = [];

                for (var i = 0; i < 20; i++) {
                    xAxisData.push('类目' + i);
                    data1.push(Math.