title: How to fix SyntaxError: fields are not currently supported error in JavaScript, Firefox?
body: <p>I've just been learning JavaScript, and I'm fairly new to coding. I was learning about properties and fields and for some reason Firefox won't run if my class contains fields.</p>
  
  <p>Here's some code that gives the error in the title.</p>
  
  <pre><code>class Animal {
    _paws = true;
  
    get paws() {
      return _paws;
    }
  }
  
  let cat = new Animal();
  
  console.log(cat.paws);
  </code></pre>