Open drop-down menu onClick in sidebar

Question

I am working on a project and I have created one navbar. In this dropdown menu also present. In this dropdown, the hover effect is there.

Now I am trying to click event and open and close dropdown's submenu. But not working. I am using only HTML and CSS.

Now on hover dropdown is open. But I am trying to do:

open and close drop-down when I click.

My code is:

/* define a fixed width for the entire menu */
.navigation {
  width: 300px;
}

/* reset our lists to remove bullet points and padding */
.mainmenu, .submenu {
  list-style: none;
  padding: 0;
  margin: 0;
}

/* make ALL links (main and submenu) have padding and background color */
.mainmenu a {
  display: block;
  background-color: #CCC;
  text-decoration: none;
  padding: 10px;
  color: #000;
}

/* add hover behaviour */
.mainmenu a:hover {
    background-color: #C5C5C5;
}


/* when hovering over a .mainmenu item,
  display the submenu inside it.
  we're changing the submenu's max-height from 0 to 200px;
*/

.mainmenu li:hover .submenu {
  display: block;
  max-height: 200px;
}

/*
  we now overwrite the background-color for .submenu links only.
  CSS reads down the page, so code at the bottom will overwrite the code at the top.
*/

.submenu a {
  background-color: #ddd;
}

/* hover behaviour for links inside .submenu */
.submenu a:hover {
  background-color: #993;
}

/* this is the initial state of all submenus.
  we set it to max-height: 0, and hide the overflowed content.
*/
.submenu {
  overflow: hidden;
  max-height: 0;
  -webkit-transition: all 0.5s ease-out;
}

<nav class="navigation">
  <ul class="mainmenu">
    <li><a href="">Home</a></li>
    <li><a href="">About</a></li>
    <li><a href="">Products</a>
      <ul class="submenu">
        <li><a href="">Tops</a></li>
        <li><a href="">Bottoms</a></li>
        <li><a href="">Footwear</a></li>
      </ul>
    </li>
    <li><a href="">Contact us</a></li>
  </ul>
</nav>

Answer 1

This is your solution

/* When the user clicks on the button, 
toggle between hiding and showing the dropdown content */
function myFunction() {
  document.getElementById("myDropdown").classList.toggle("show");
}

// Close the dropdown if the user clicks outside of it
window.onclick = function(event) {
  if (!event.target.matches('.dropbtn')) {
    var dropdowns = document.getElementsByClassName("dropdown-content");
    var i;
    for (i = 0; i < dropdowns.length; i++) {
      var openDropdown = dropdowns[i];
      if (openDropdown.classList.contains('show')) {
        openDropdown.classList.remove('show');
      }
    }
  }
}

.navigation{
	width: 300px;
}

.mainmenu,
.submenu {
  list-style: none;
  padding: 0;
  margin: 0;
}

.mainmenu a {
  display: block;
  background-color: #CCC;
  text-decoration: none;
  padding: 10px;
  color: #000;
}

.mainmenu a:hover {
  background-color: #C5C5C5;
}

/**/

.dropbtn {
  background-color: #ccc;
  color: #000;
  border: none;
  cursor: pointer;
  padding: 10px;
  display: block;
}

.dropbtn:hover, .dropbtn:focus {
  background-color: #ccc;
}

.dropbtn:hover{
	 background-color: #C5C5C5;
}

.dropdown {
  position: relative;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #ddd;
  min-width: 160px;
  overflow: auto;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
  width: 300px;
}

.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}

.dropdown a:hover {background-color: #993;}

.show {display: block;}

<nav class="navigation">
  <ul class="mainmenu">
   <li><a>Home</a></li>
    <li><a>About</a></li>
     <div class="dropdown">
      <li onclick="myFunction()" class="dropbtn">Products</li>
       <div id="myDropdown" class="dropdown-content">
         <a>Tops</a>
         <a>Bottoms</a>
         <a>Footwear</a>
       </div>
     </div>
  <li><a href="">Contact us</a></li>
  </ul>
</nav>

u can achieve with javascript and this is right solution

Answer 2

You can use a checkbox (<input type="checkbox">) with the adjacent sibling combinator (+) to toggle the sub menu. Convert the link (a) to a label. Set the label's for attribute to the input's id, and hide the input using display: none.

/* define a fixed width for the entire menu */

.navigation {
  width: 300px;
}


/* reset our lists to remove bullet points and padding */

.mainmenu,
.submenu {
  list-style: none;
  padding: 0;
  margin: 0;
}


/* make ALL links (main and submenu) have padding and background color */

.mainmenu a,
.mainmenu label {
  display: block;
  background-color: #CCC;
  text-decoration: none;
  padding: 10px;
  color: #000;
}

.mainmenu input {
  display: none;
}


/* add hover behaviour */

.mainmenu a:hover {
  background-color: #C5C5C5;
}


/* when hovering over a .mainmenu item,
  display the submenu inside it.
  we're changing the submenu's max-height from 0 to 200px;
*/

.mainmenu :checked+.submenu {
  display: block;
  max-height: 200px;
}


/*
  we now overwrite the background-color for .submenu links only.
  CSS reads down the page, so code at the bottom will overwrite the code at the top.
*/

.submenu a {
  background-color: #ddd;
}


/* hover behaviour for links inside .submenu */

.submenu a:hover {
  background-color: #993;
}


/* this is the initial state of all submenus.
  we set it to max-height: 0, and hide the overflowed content.
*/

.submenu {
  overflow: hidden;
  max-height: 0;
  -webkit-transition: all 0.5s ease-out;
}

<nav class="navigation">
  <ul class="mainmenu">
    <li><a href="">Home</a></li>
    <li><a href="">About</a></li>
    <li><label for="products">Products</label><input type="checkbox" id="products">
      <ul class="submenu">
        <li><a href="">Tops</a></li>
        <li><a href="">Bottoms</a></li>
        <li><a href="">Footwear</a></li>
      </ul>
    </li>
    <li><a href="">Contact us</a></li>
  </ul>
</nav>