话不多少，先看官方解释

我这个简单，所以所有说明都在图上了

handleSummary({ columns, data }){console.log(columns, data)let sums = {}columns.forEach((item,index)=>{const key = item.key;console.log("key",item)if(index == 0){console.log("k")sums[key] = {key,value: '汇总'};}else if(index == 1){sums[key] = {key,value: this.countvariableValue};}else{sums[key] = {key,value: ''};}console.log(key)})return sums;}