js面试题——找到数组中的重复元素并判断重复次数且输出重复元素

var countArr = [1,2,3,4,5,6,3,4,3,3,7,8,9,32,1,11,2,3,3,3];
    var res = {};
    var maxnum=0;
    var max;
    function getRepeat(arr){
      for (var i = 0; i < arr.length; i++) {
          if(!res[arr[i]]){
              res[arr[i]] = 1;
          }else{
              res[arr[i]] ++;
          }
      };
      var keys = Object.keys(res);
      console.log(keys);
      for(var j=0;j<keys.length;j++){
          if(res[keys[j]] > maxnum){
              maxnum = res[keys[j]];
              max = keys[j];
          }
      }
      return maxnum + max
    }
    getRepeat(countArr);
    console.log('出现次数最多的是' + max + '次数为' + maxnum);

输出结果：出现次数最多的是3次数为7