js----数组对象中根据某个相同的属性值合并其他项

    let arr = [
      { id: 1, list: { id: 66 } },
      { id: 1, list: { id: 44 } },
      { id: 2, list: { id: 55 } },
      { id: 2, list: { id: 33 } },
      { id: 3, list: { id: 11 } },
      { id: 3, list: { id: 22 } }
    ]

    let tempArr = [], newArr = []
    for (let i = 0; i < arr.length; i++) {
      if (tempArr.indexOf(arr[i].id) === -1) {
        newArr.push({
          id: arr[i].id,
          list: [arr[i].list]
        })
        tempArr.push(arr[i].id);
      } else {
        for (let j = 0; j < newArr.length; j++) {
          if (newArr[j].id == arr[i].id) {
            newArr[j].list.push(arr[i].list)
          }
        }
      }
    }

    console.log(newArr)

 

场景：

    getTableData() {
      this.$observer.$on("selectedProject", data => {
        let list = [];
        data.forEach(item => {
          if (item.select === 1) list.push(item);
        });
        this.tableData = list;
        console.log(data, this.tableData);
        this.tableData.forEach(item => {
          item.arr = this.merger(item.lisVos);
　　　　　　// 根据reportTime排序
          item.arr.sort(function(a, b) {
            if (a.reportTime < b.reportTime) {
              return -1;
            } else if (a.reportTime == b.reportTime) {
              return 0;
            } else {
              return 1;
            }
          });
          let str = "";
          item.arr.forEach(ele => {
            str += ele.details + "；" + "\n";
          });
          item.details = str;
        });
      });
    },
    // 传入一个数组，将reportTime相同的对象中的name合并到details中
    merger(arr) {
      let tempArr = [],
        newArr = [];
      for (let i = 0; i < arr.length; i++) {
        if (tempArr.indexOf(arr[i].reportTime) === -1) {
          newArr.push({
            reportTime: arr[i].reportTime,
            name: [arr[i].name]
          });
          tempArr.push(arr[i].reportTime);
        } else {
          for (let j = 0; j < newArr.length; j++) {
            if (newArr[j].reportTime == arr[i].reportTime) {
              newArr[j].name.push(arr[i].name)
            }
          }
        }
      }
　　　 // 给newArr添加一个新字段details
      newArr.forEach(item => {
        item.details = item.reportTime + "：" + item.name
      })
      return newArr;
    }