echart2.x 添加legend 绑定事件

var ecConfig = echarts.config;<br>（有些情况：var ecConfig = require('echarts/config')）

<em id="__mceDel">myChart.on(ecConfig.EVENT.LEGEND_SELECTED, function(params) { // legendselected   legendselectchanged
      console.log('obj', params)
      var selected = obj.selected;
      var legend = obj.name;
 
      // 使用 legendToggleSelect Action 会重新触发 legendselectchanged Event，导致本函数重复运行
      // 使得 无 selected 对象
      if (selected != undefined) {
         if (isFirstUnSelect(selected)) {
             triggerAction('legendToggleSelect', selected);
         } else if (isAllUnSelected(selected)) {
             triggerAction('legendSelect', selected);
         }
      }
    });
</em>