数组归类

groupDepart(arr){
      var map = {},
      dest = [];
      for(var i = 0; i < arr.length; i++){
          var ai = arr[i];
          if(!map[ai.departCode]){
              dest.push({
                  departCode: ai.departCode,
                  dname: ai.dname,
                  data: [ai]
              });
              map[ai.departCode] = ai;
          }else{
              for(var j = 0; j < dest.length; j++){
                  var dj = dest[j];
                  if(dj.departCode == ai.departCode){
                      dj.data.push(ai);
                      break;
                  }
              }
          }
      }
      console.log(dest,'.....')
    },

　　经常遇到的一个写法