Modifying a webpage

<h1> Title </h1>
<p>
  Hello <em>world</em> <strong>!</strong>
  </p><div class="links">
    <a href="">A 
      <strong>link</strong> </a>
  </div>
<p></p>

const element = document.querySelector("h1");
element.textContent = "Modified in JavaScript !"