Error with menu button toggle css js html

I would like to use part of this code from codepen on my website but the menu button does not currently work. I do not know what the problem is so I have not tried anything to solve it. The code works flawlessly on codepen but stops working when use in visual studio. The HTML code is:

<section class="showcase">
    <header>
      <h2 class="logo">Travel</h2>
      <div class="toggle"></div>
    </header>
    <video src="https://traversymedia.com/downloads/videos/explore.mp4" muted loop autoplay></video>
    <div class="overlay"></div>
    <div class="text">
      <h2>Never Stop To </h2> 
      <h3>Exploring The World</h3>
      <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
      tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
      quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
      consequat.</p>
      <a href="#">Explore</a>
    </div>
    <ul class="social">
      <li><a href="#"><img src="https://i.ibb.co/x7P24fL/facebook.png"></a></li>
      <li><a href="#"><img src="https://i.ibb.co/Wnxq2Nq/twitter.png"></a></li>
      <li><a href="#"><img src="https://i.ibb.co/ySwtH4B/instagram.png"></a></li>
    </ul>
  </section>
  <div class="menu">
    <ul>
      <li><a href="#">Home</a></li>
      <li><a href="#">News</a></li>
      <li><a href="#">Destination</a></li>
      <li><a href="#">Blog</a></li>
      <li><a href="#">Contact</a></li>
    </ul>
  </div>

The CSS:

@import url('https://fonts.googleapis.com/css?family=Poppins:200,300,400,500,600,700,800,900&display=swap');
*
{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Poppins', sans-serif;
}
header
{
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  padding: 40px 100px;
  z-index: 1000;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
header .logo
{
  color: #fff;
  text-transform: uppercase;
  cursor: pointer;
}
.toggle
{
  position: relative;
  width: 60px;
  height: 60px;
  background: url(https://i.ibb.co/HrfVRcx/menu.png);
  background-repeat: no-repeat;
  background-size: 30px;
  background-position: center;
  cursor: pointer;
}
.toggle.active
{
  background: url(https://i.ibb.co/rt3HybH/close.png);
  background-repeat: no-repeat;
  background-size: 25px;
  background-position: center;
  cursor: pointer;
}
.showcase
{
  position: absolute;
  right: 0;
  width: 100%;
  min-height: 100vh;
  padding: 100px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: #111;
  transition: 0.5s;
  z-index: 2;
}
.showcase.active
{
  right: 300px;
}

.showcase video
{
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.8;
}
.overlay
{
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: #03a9f4;
  mix-blend-mode: overlay;
}
.text
{
  position: relative;
  z-index: 10;
}

.text h2
{
  font-size: 5em;
  font-weight: 800;
  color: #fff;
  line-height: 1em;
  text-transform: uppercase;
}
.text h3
{
  font-size: 4em;
  font-weight: 700;
  color: #fff;
  line-height: 1em;
  text-transform: uppercase;
}
.text p
{
  font-size: 1.1em;
  color: #fff;
  margin: 20px 0;
  font-weight: 400;
  max-width: 700px;
}
.text a
{
  display: inline-block;
  font-size: 1em;
  background: #fff;
  padding: 10px 30px;
  text-transform: uppercase;
  text-decoration: none;
  font-weight: 500;
  margin-top: 10px;
  color: #111;
  letter-spacing: 2px;
  transition: 0.2s;
}
.text a:hover
{
  letter-spacing: 6px;
}
.social
{
  position: absolute;
  z-index: 10;
  bottom: 20px;
  display: flex;
  justify-content: center;
  align-items: center;
}
.social li
{
  list-style: none;
}
.social li a
{
  display: inline-block;
  margin-right: 20px;
  filter: invert(1);
  transform: scale(0.5);
  transition: 0.5s;
}
.social li a:hover
{
  transform: scale(0.5) translateY(-15px);
}
.menu
{
  position: absolute;
  top: 0;
  right: 0;
  width: 300px;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}
.menu ul
{
  position: relative;
}
.menu ul li
{
  list-style: none;
}
.menu ul li a
{
  text-decoration: none;
  font-size: 24px;
  color: #111;
}
.menu ul li a:hover
{
  color: #03a9f4; 
}

@media (max-width: 991px)
{
  .showcase,
  .showcase header
  {
    padding: 40px;
  }
  .text h2
  {
    font-size: 3em;
  }
  .text h3
  {
    font-size: 2em;
  }
}

And the JS:

 const menuToggle = document.querySelector('.toggle');
      const showcase = document.querySelector('.showcase');

      menuToggle.addEventListener('click', () => {
        menuToggle.classList.toggle('active');
        showcase.classList.toggle('active');
      })

Is there any way to fix this issue? Any help is appriciated!

Answer

Change you script as this:

<script>
    window.addEventListener('load', () => {
        const menuToggle = document.querySelector('.toggle');
        const showcase = document.querySelector('.showcase');

        menuToggle.addEventListener('click', () => {
            menuToggle.classList.toggle('active');
            showcase.classList.toggle('active');
        })
    });
</script>