title: html Text content not updating
body: <p>I'm trying to make an incremental game. but when I test it out the game doesn't increment clicks, everything looks fine. So what am I doing wrong?</p>
  <p>Thanks in advance :)</p>
  <p><strong>JavaScript Code(in separate file)</strong></p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>//Unused or copied code
  //  mass += energy;
  //  btn.innerText = mass + "mass";
  //DOM
  let btn = document.getElementById("btn");
  let img = document.getElementById("img");
  
  //Variables
  var mass = 0;
  var energy = 1;
  var version = 0.1 + 'oab';
  
  //El(s)
  img.addEventListener('click', e =&gt; {
    mass += energy;
    let btn.textContent = mass + " Mass";
  });</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;input type="image" id="img" src="assets/sun.jpg" name="button" alt="clicker" width="250" height="250"&gt;&lt;br&gt;
  &lt;h1 id='btn'&gt;0 Mass&lt;/h1&gt;</code></pre>
  </div>
  </div>
  </p>