JSFiddle - React, Tailwind, and code Playground

JavaScript

var interval = {};    

function gfu(parameter)
         { 
                  var loc = location.search.substring(1, location.search.length);
                  var param_value = false;
                  var params = loc.split("&");
                  for (i=0; i<params.length;i++)
                  {
                      param_name = params[i].substring(0,params[i].indexOf('='));
                      if (param_name == parameter)
                      {
                           param_value = params[i].substring(params[i].indexOf('=')+1)
                      }
                  }
                  if (param_value)
                  {
                      return param_value;
                  }
                  else
                  {
                      return false;
                  }
            }
    function showCanvas(no)
    {
        if (no != "no")
        {
            document.getElementById('startGameBox').style.display = "none";
        }
        document.getElementById('canvas').style.display = "block";
        document.getElementById('endgame').style.display = "none";
    }
    function playAgain(winner,donedying)
    {
        if (donedying == true && winner == false)
        {
            if (realwinner = "skier")
            {
                skiwins++;
            }
            else if (realwinner == "snowboarder")
            {
                sbwins++;
            }
            else
            {
                ties++;
            }
            reset();
            keysDown = {};
            sbhealth = sbrealhealth;
            skihealth = skirealhealth;
            interval = window.setInterval(function(){main()}, 1);
        }
        else
        {
            var realwinner = winner;
            var dietime = setTimeout(function(){playAgain(false,true)}, 1000);
            window.clearInterval(interval);
        }
    }
    function vp(woh)
    {
            var viewportwidth;
             var viewportheight;
  
             if...