根据对应的key值对数组对象进行分类

      var res = [
        {
          frtId: "1",
          frtName: "中国",
          frtCode: null,
          frpType: "1414708",
          frpName: "01计税表",
          reportNnum: "3"
        },
        {
          frtId: "1",
          frtName: "中国",
          frtCode: null,
          frpType: "1414709",
          frpName: "02管理",
          reportNnum: "3"
        },
        {
          frtId: "1",
          frtName: "中国",
          frtCode: null,
          frpType: "1414710",
          frpName: "03安永",
          reportNnum: "2"
        },
        {
          frtId: "1",
          frtName: "中国",
          frtCode: null,
          frpType: "1414711",
          frpName: "04报税截图",
          reportNnum: "3"
        },
        {
          frtId: "1",
          frtName: "中国",
          frtCode: null,
          frpType: "1414712",
          frpName: "05其他税务文件",
          reportNnum: "1"
        },
        {
          frtId: "2",
          frtName: "北京",
          frtCode: null,
          frpType: "1414708",
          frpName: "01计税表",
          reportNnum: "3"
        },
        {
          frtId: "2",
          frtName: "北京",
          frtCode: null,
          frpType: "1414709",
          frpName: "02管理",
          reportNnum: "3"
        },
        {
          frtId: "2",
          frtName: "北京",
          frtCode: null,
          frpType: "1414710",
          frpName: "03安永",
          reportNnum: "2"
        },
        {
          frtId: "2",
          frtName: "北京",
          frtCode: null,
          frpType: "1414711",
          frpName: "04报税截图",
          reportNnum: "3"
        },
        {
          frtId: "2",
          frtName: "北京",
          frtCode: null,
          frpType: "1414712",
          frpName: "05其他税务文件",
          reportNnum: "1"
        }
      ];

      /**
       * 根据某个key值进行分类,res是数据，key根据建名进行分类
       * @param {*} res 要进行分类的数组对象
       * @param {*} key 要根据的key值进行分类 (字符串)
        @param {*} title 每个大量分类的标题 （没有这个需要可以不传）（字符串）
       */
      function data(res, key, title) {
          console.log('res',res)
        if (!title) {
          title = key;
        }
        let tmpObj = {};
        res.map(function(subArr) {
          var o = tmpObj[subArr[key]];
          if (!o) {
            o = {};
            o.data = [];
            o.title = subArr[title];
            o.data.push(subArr);
            tmpObj[subArr[key]] = o;
          } else {
            o.data.push(subArr);
          }
          return o;
        });
        return tmpObj;
      }
    //调用方法
    data([res],'frtId','frtName')
    </script>

分类的简单写法

  /**
         * 根据某个key值进行分类,res是数据，以`key`的值作为键名
         * @param {*} res 要进行分类的数组对象
         * @param {*} key 要根据的key值进行分类 (字符串)
         */
      function classifiObj(data,key){
        let Report={}
        data.forEach((item,index)=>{
          if(Report[item[key]]){
            Report[item[key]].push(item)
          }else{
            Report[item[key]]=[]
            Report[item[key]].push(item)
          }
        })
        return Report
      }

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