echart 自定义提示语

formatter: function(params){
   let html = ""
   let total = 0
   params.forEach(value=>{
       html += "<span style='display:inline-block;margin-right:5px;border-radius:10px;width:9px;height:9px;background-color:"+value.color+";'></span>"+ value.seriesName + ":"+ value.data+"<br>"
       total += Number(value.data)
   })
   html += "总计: "+ total
   return html
}