Untitled

<!DOCTYPE html>
<html lang="es">
  <head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  </head>
  <body>
    <header>
    <h1>Test</h1>
    <nav id="loadedNav"></nav>


    </header>
    <footer>



    </footer>

<script>
  $(function(){
    $.get( "nav.html", function( data ) {
      $( "#loadedNav" ).html( data );
    });
  });
</script>

  </body>
  
</html>

// Code goes here

/* Styles go here */

<ul>
  <li>Item 1</li>
  <li>Item 2</li>
</ul>