JSFiddle - React, Tailwind, and code Playground

JavaScript

var maxCount = 0;
var maxCountNumber = 0;

for (var y = 1000000; y >= 1; y--) {
  var count = executeAlgo(y);
  if (count > maxCount) {
    maxCount = count;
    maxCountNumber = y;
  }

}

console.log('Maximum count is for:' + maxCountNumber);
console.log('Maximum count: '+ maxCount);
alert('Maximum count is for: ' + maxCountNumber + '; Maximum count: '+ maxCount);

function executeAlgo(x) {
  var num = x;
  var count = 1;
  while (x > 1) {
    if ((x % 2) == 0) {
      const j = x / 2;
      x = j;
    } else {
      const k = (x * 3) + 1;
      x = k;
    }
    count++;

  }
  //console.log(num + 'Count: ' + count);
  return count;
}