Can you use a substitute for the keyword const?

I’m trying to make a simple counter, but its proving difficult, $ was undefined, but I used:

function jQuery($) {
  'use strict';
  $(function() {
    //code here
  });
};

While that fixed the $ problem, i can’t figure out how to make the counter. This is my code:

var counter = 0;
    
function appendNumber() {
  const newElement = document.createElement('div');
  newElement.textContent = counter;
  document.body.appendChild(newElement);
  counter++;
}

It says it’s reserved i need some other way to do const, as it says “The keyword const is reserved.”
If you find a solution to this, or a different way to do a counter, it would be much appreciated.

I tried just using a var, then using append, but it just appended x. (the var’s name)
This was some of the code I tried:

function jQuery($) {
  'use strict';
  function findAnswer() {
    x = parseInt(x);
  }
  $(function() {
    var $counter = $( ".counter" );
    if (x < 0) {
      answer = x * y;
    }
    $( ".counter" ).append("answer");
    $( ".clickme" ).on("click", function() {
      answer++;
      $( ".counter" ).append ("answer")
    });
  });
}

The parseInt was an idea I had, because is school, it had me make a calculator, using parseInt.