title: Vanilla JS equivalent to JQuery function $.on
body: <p>Here is some sample code of a ton of the exact same function in the project.</p>
  <pre><code>$('#psi').on('change', function() {
    if($(this).is(&quot;:checked&quot;)) {
      $('.psiOptions').removeClass('hidden-1');
    } else {
      $('.psiOptions').addClass('hidden-1');
    }
  });
  </code></pre>
  <p>I'm trying to upgrade this to not rely on JQuery. What is the most correct way to do this in Vanilla JS besides assigning onclick=&quot;someFunction()&quot; 20 different times for 20 different cases?</p>