How to Create a Custom Multiple Selection Dropdown Checklist with Checkboxes in HTML, CSS, and JavaScript?

Creating Multiple Selection Dropdown Checklists

When creating a dropdown list, it's often desirable to allow users to select multiple options. Using HTML, this can be achieved by employing checkboxes within the dropdown options.

Conventional Dropdown with Checkboxes:

When adding checkboxes to a dropdown list without additional code, the checkboxes appear in front of the dropdown field. To change this, a more advanced approach is required.

Implementing a Custom Dropdown Checklist:

The following code snippet demonstrates how to create a custom dropdown checklist:

<div>

.dropdown-check-list {
  display: inline-block;
}

.dropdown-check-list .anchor {
  position: relative;
  cursor: pointer;
  display: inline-block;
  padding: 5px 50px 5px 10px;
  border: 1px solid #ccc;
}

.dropdown-check-list .anchor:after {
  position: absolute;
  content: "";
  border-left: 2px solid black;
  border-top: 2px solid black;
  padding: 5px;
  right: 10px;
  top: 20%;
  -moz-transform: rotate(-135deg);
  -ms-transform: rotate(-135deg);
  -o-transform: rotate(-135deg);
  -webkit-transform: rotate(-135deg);
  transform: rotate(-135deg);
}

.dropdown-check-list .anchor:active:after {
  right: 8px;
  top: 21%;
}

.dropdown-check-list ul.items {
  padding: 2px;
  display: none;
  margin: 0;
  border: 1px solid #ccc;
  border-top: none;
}

.dropdown-check-list ul.items li {
  list-style: none;
}

.dropdown-check-list.visible .anchor {
  color: #0094ff;
}

.dropdown-check-list.visible .items {
  display: block;
}

var checkList = document.getElementById('list1');
checkList.getElementsByClassName('anchor')[0].onclick = function(evt) {
  if (checkList.classList.contains('visible'))
    checkList.classList.remove('visible');
  else
    checkList.classList.add('visible');
};

Explanation:

• HTML: The HTML structure creates a basic dropdown with an anchor element representing the dropdown header and an unordered list containing the dropdown options with checkboxes.
• CSS: The CSS styles define the layout and appearance of the dropdown, including the checkbox styling and the display behavior of the dropdown options.
• JavaScript: The JavaScript code handles the opening and closing of the dropdown options when the anchor element is clicked.

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