数组分组

      getRepeatNum(arr) {//找出数组中相同的元素
        let obj = {};
        for (let i = 0, len = arr.length; i < len; i++) {
          if (obj[arr[i]] == undefined) {
            obj[arr[i]] = 1;
          } else {
            obj[arr[i]]++;
          }
        }
        for (let key in obj) {
          obj[key] <= 1 && delete obj[key];
        }
        return Object.keys(obj);
      },
      getGroupNum(arr) {//根据数组的某个参数进行分组
        let newArry = {};
        for (let i = 0; i < arr.length; i++) {
          if (newArry[arr[i].num.errcode]) {
            newArry[arr[i].num.errcode].push(arr[i].num.num)
          }
          else {
            newArry[arr[i].num.errcode] = [arr[i].num.num]
          }
        }
        return newArry
      },