跪求大神给以下代码是什么意思（给个注释），我看老半天了

Question

<script> var getOption = function(chartType) { var chartOption = chartType == 'pie' ? { calculable: false, series: [{ name: '访问来源', type: 'pie', radius: '65%', center: ['50%', '50%'], data: [{ value: 335, name: '直接访问' }, { value: 310, name: '邮件营销' }, { value: 234, name: '联盟广告' }, { value: 135, name: '视频广告' }, { value: 1548, name: '搜索引擎' }] }] } : { legend: { data: ['蒸发量', '降水量'] }, grid: { x: 35, x2: 10, y: 30, y2: 25 }, toolbox: { show: false, feature: { mark: { show: true }, dataView: { show: true, readOnly: false }, magicType: { show: true, type: ['line', 'bar'] }, restore: { show: true }, saveAsImage: { show: true } } }, calculable: false, xAxis: [{ type: 'category', data: ['1月', '2月', '3月', '4月', '5月', '6月', '7月', '8月', '9月', '10月', '11月', '12月'] }], yAxis: [{ type: 'value', splitArea: { show: true } }], series: [{ name: '蒸发量', type: chartType, data: [2.0, 4.9, 7.0, 23.2, 25.6, 76.7, 135.6, 162.2, 32.6, 20.0, 6.4, 3.3] }, { name: '降水量', type: chartType, data: [2.6, 5.9, 9.0, 26.4, 28.7, 70.7, 175.6, 182.2, 48.7, 18.8, 6.0, 2.3] }] }; return chartOption; }; var byId = function(id) { return document.getElementById(id); }; var barChart = echarts.init(byId('barChart')); barChart.setOption(getOption('bar')); var lineChart = echarts.init(byId('lineChart')); lineChart.setOption(getOption('line')); var pieChart = echarts.init(byId('pieChart')); pieChart.setOption(getOption('pie')); byId("echarts").addEventListener('tap',function(){ var url = this.getAttribute('data-url'); plus.runtime.openURL(url); },false); </script>