How do I create a functioning hamburger menu? – Blancer.com Tutorials and projects

So I have tried to create a hamburger menu and have faced no luck. Whenever I click on the menu icon, it changes to an ‘X’ however it does not open the menu. I have been trying for the last couple of days, and have also researched but have found nothing that works.

Here is my HTML code for the navmenu and hamburger icon:

let menu = document.querySelector('#menu-icon');
let navmenu = document.querySelector('.navmenu');

menu.onclick = () => {
  menu.classList.toggle('bx-x');
  navmenu.classList.toggle('open');
}

.navmenu {
  display: flex;
}

.navmenu a {
  color: #000;
  font-size: 16px;
  text-transform: capitalize;
  padding: 10px 20px;
  font-weight: 400;
  transition: all .42s ease;
}

.navmenu a:hover {
  color: #03A9F4;
}

.nav-icon {
  display: flex;
  align-items: center;
}

.nav-icon i {
  margin-right: 20px;
  color: #ffffff;
  font-size: 25px;
  font-weight: 400;
  transition: all .42s ease;
}

.nav-icon i:hover {
  transform: scale(1.1);
  color: #03A9F4;
}

#menu-icon {
  font-size: 35px;
  display: none;
  color: #ffffff;
  z-index: 10001;
  cursor: pointer;
}

@media(max-width: 750px) {
  #menu-icon {
    display: block;
  }
  .navmenu {
    position: absolute;
    top: -100%;
    right: 0%;
    width: 300px;
    height: 130vh;
    background: #000;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 120px 30px;
    transition: all .42s;
  }
  .navmenu a {
    display: block;
    margin: 10px 0;
  }
  .navmenu.open {
    right: 0%
  }
}

<a href="#" class="logo"><img src="images/logo5.png" alt="" class="prevent-select"></a>
<ul class="navmenu">
  <li><a href="#" id="prevent-select" class="hover-underline-animation">Home</a></li>
  <li><a href="#" id="prevent-select" class="hover-underline-animation">Shop</a></li>
  <li><a href="#" class="hover-underline-animation" id="prevent-select">Sale</a></li>
  <li><a href="#" class="hover-underline-animation" id="prevent-select">Contact</a></li>
  <li><a href="#" class="hover-underline-animation" id="prevent-select">Policies</a></li>
  <li><a href="#" class="hover-underline-animation" id="prevent-select">More</a></li>
</ul>
<div class="nav-icon">
  <a href="#" id="prevent-select"><i class='bx bx-search-alt-2'></i></a>
  <div class="dropdown2">
    <button class="dropbtn2">
                        <a href="#" id="prevent-select"><i class='bx bx-user'></i></a>
                    </button>
    <div class="dropdown-content2">
      <div class="login">
        <ul>
          <a href="login_register.php" id="prevent-select">Log in/Register</a>
        </ul>
      </div>
    </div>
  </div>
  <a href="#" id="prevent-select"><i class='bx bx-shopping-bag'></i></a>
  <div class="bx bx-menu" id="menu-icon"></div>
</div>

I tried this but it did not work as it had resulted in what I had mentioned above. I basically want it to slide the menu open when I click the hamburger menu icon.