JSFiddle - React, Tailwind, and code Playground

JavaScript

arr1 = [];
arr2 = [];

for(i=0; i<50000; i++) {
    arr1[i] = Math.floor(Math.random() * 50)
    arr2[i] = arr1[i]
}

    function mine(arr){
      arr.sort(function(a, b){return a-b})
      var count = 0;
      var integer = 0;
      var tempCount = 1;
      var tempInteger = 0;
      var prevInt = null
      for(var i=0;i<arr.length;i++){
        tempInteger = arr[i]
        if(i > 0){
          prevInt = arr[i-1]
        }
        if(prevInt == arr[i]){
          tempCount += 1
          if(tempCount > count){
            count = tempCount
            integer = tempInteger
          }
        }else{
          tempCount = 1
        }
      }
      console.log("most repeated is: " + integer)
    }
    function theirs(a){
      var count = 1, tempCount;
      var popular = a[0];
      var temp = 0;
      for (var i = 0; i < (a.length - 1); i++)
      {
        temp = a[i];
        tempCount = 0;
        for (var j = 1; j < a.length; j++)
        {
          if (temp == a[j])
            tempCount++;
        }
        if (tempCount > count)
        {
          popular = temp;
          count = tempCount;
        }
      }
      console.log("most repeated is: " + popular)
    }
console.time("mine")
mine(arr1)
console.timeEnd("mine")
console.time("theirs")
theirs(arr2)
console.timeEnd("theirs")