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>