element ui表格合并span-method

mergeLineMethod (){//处理合并表格数据
            this.mergeLineArr = []
            this.mergeLineIndex = 0
            let mergeLine = this.list
            mergeLine.forEach((res, i) => {
                if (i === 0) {
                    this.mergeLineArr.push(1);
                    this.mergeLineIndex= 0
                } else {
                    // 判断当前元素与上一个元素是否相同,是就给之前相同的第一个+1，并且数组添加一个0
                    if (mergeLine[i].id === mergeLine[i - 1].id) {
                        this.mergeLineArr[this.mergeLineIndex] += 1;
                        this.mergeLineArr.push(0);
                    } else {//如果与前一个不相同，则追加一个新从1开始的数字，此时更新mergeLineIndex的值
                        this.mergeLineArr.push(1);
                        this.mergeLineIndex= i;
                    }
                } 
            });
        },
        mergeCell ({row,column,rowIndex,columnIndex}){
            let notColArr = [4, 5, 6, 7, 8, 12, 14]
            if (!notColArr.includes(columnIndex)) {
                const _row = this.mergeLineArr[rowIndex];
                const _col = _row > 0 ? 1 : 0;
                return {
                    rowspan: _row,
                    colspan: _col
                }
            }
        },