Convert HTML List Into Dropdown Menu – Dropdown-List

A small vanilla JavaScript library that transforms the regular HTML unordered list into a drop-down menu for easily navigating between your web pages.

How to use it:

Create a normal unordered list as follows:

<ul class="drop">
  <li><a href="#1">Menu Item 1</a></li>
  <li><a href="#2">Menu Item 2</a></li>
  <li><a href="#3">Menu Item 3</a></li>
  <li><a href="#4">Menu Item 4</a></li>
  <li class="last"><a href="">Menu Item 5</a></li>
</ul>

The core JavaScript for the drop-down menu.

var activeClass = "is-active"
var forEach = function (array, callback, scope) {
  for (var i = 0; i < array.length; i++) {
    callback.call(scope, i, array[i]); // passes back stuff we need from the array
  }
};
forEach(document.querySelectorAll(".dropdown_list span.dropdown"), function (index, value) {
  value.addEventListener('click', function() {
        //console.log(value.classList);
        if ( !value.classList.contains(activeClass) ) {
            var el = document.querySelectorAll(".dropdown_list span.dropdown");
            var i; for (i = 0; i < el.length; i++) {
                el[i].classList.remove(activeClass);
            }
            value.classList.toggle(activeClass);
        } else
        if ( value.classList.contains(activeClass) ) {
            value.classList.remove(activeClass);
        }
  })
});
document.addEventListener('click', function(e) {
  // Dropdown Select Toggle
  var el = document.querySelectorAll(".dropdown_list span.dropdown")
  var e=e? e : window.event;
    var event_element=e.target? e.target : e.srcElement;
  if (!event_element.closest(".dropdown_list")){
    //console.log(event_element.closest(".dropdown_list"));
    var i; for (i = 0; i < el.length; i++) {
      el[i].classList.remove(activeClass);
    }
  }
}, false);

The necessary polyfills for old browsers.

// .classList() Polyfill for older browser - IE9 again...
!function(){function t(t){this.element=t}var e=function(t){return RegExp("(^| )"+t+"( |$)")},n=function(t,e,n){for(var i=0;i<t.length;i++)e.call(n,t[i])}
t.prototype={add:function(){n(arguments,function(t){this.contains(t)||(this.element.className+=" "+t)},this)},remove:function(){n(arguments,function(t){this.element.className=this.element.className.replace(e(t),"")},this)},toggle:function(t){return this.contains(t)?(this.remove(t),!1):(this.add(t),!0)},contains:function(t){return e(t).test(this.element.className)},replace:function(t,e){this.remove(t),this.add(e)}},"classList"in Element.prototype||Object.defineProperty(Element.prototype,"classList",{get:function(){return new t(this)}}),window.DOMTokenList&&null==DOMTokenList.prototype.replace&&(DOMTokenList.prototype.replace=t.prototype.replace)}()
// .closest() Polyfill for browsers that supports document.querySelectorAll() - IE9 again...
if (window.Element && !Element.prototype.closest) {
  Element.prototype.closest =
  function(s) {
      var matches = (this.document || this.ownerDocument).querySelectorAll(s),
          i,
          el = this;
      do {
          i = matches.length;
          while (--i >= 0 && matches.item(i) !== el) {};
      } while ((i < 0) && (el = el.parentElement));
      return el;
  };
}

The example CSS for the drop-down menu.

.dropdown_list {
  margin: 15px auto;
  width: auto;
  position: relative;
  box-sizing: border-box;
}
.dropdown_list li {
  margin: 0;
  padding: 0;
  list-style: none;
}
.dropdown_list span.dropdown {
  display: block;
  margin: 0;
  padding: 0 10px;
  width: auto;
  height: 40px;
  line-height: 38px;
  background: #fff;
  border-radius: 3px;
  border: 1px solid #a1c4e5;
  cursor: pointer;
  overflow: hidden;
}
.dropdown_list span.dropdown.is-active {
  border-radius: 3px 3px 0 0;
}
.dropdown_list span.dropdown:hover, .dropdown_list span.dropdown:active {
  background: #f1f1f1;
  -webkit-tap-highlight-color: rgba(0,0,0,0);
}
.dropdown_list span.dropdown:after {
  float: right;
  margin-top: 0;
  margin-left: 10px;
  width: 15px;
  height: 100%;
  content: "\e817";
  color: ineherit;
  font-family: 'icons';
  text-align: center;
  font-size: inherit;
  vertical-align: top;
}
.dropdown_list span.dropdown.is-active:after {
  content: "\e816"
}
.dropdown_list a:hover {
  text-decoration: none;
  border-bottom: 0;
}
.dropdown_list .drop {
  display: block;
  float: left;
  margin: 0;
  width: 100%;
  max-height: 0;
  position: absolute;
  background: #fff;
  top: 40px;
  border-radius: 0 0 3px 3px;
  z-index: 10;
  overflow-y: auto;
  opacity: 0;
  transition: max-height 0.3s cubic-bezier(0, 0.6, 0, 1), opacity 0.3s cubic-bezier(0, 0.6, 0, 1);
}
.dropdown_list span.is-active + .drop {
  max-height: 350px;
  border: 1px solid #a1c4e5;
  border-top: 0;
  opacity: 1;
  transition: max-height 0.2s ease-in-out, opacity 0.2s ease-in-out;
}
.dropdown_list .drop li {
  float: none;
  display: block;
  margin: 0;
  padding: 0;
  border: 0;
  height: auto;
  border-top: 1px dotted #ccc;
}
.dropdown_list .drop li:first-child {
  border-top: 0
}
.dropdown_list .drop li a {
  float: none;
  display: block;
  margin: 0;
  padding: 6px 10px 6px 25px;
  height: auto;
  width: auto;
  text-transform: none;
  color: inherit;
  background: #fff;
  text-align: left;
  border-radius: 0;
  border: 0;
}
.dropdown_list .drop li a:hover, .dropdown_list .drop li a:active {
  background: #f1f1f1;
}
.dropdown_list .drop li a:before {
  display: inline-block;
  margin-left: -15px;
  margin-right: 5px;
  width: 10px;
  height: inherit;
  content: "\00BB";
  color: inherit;
  font-family: 'icons';
  text-align: center;
  font-size: inherit;
  vertical-align: top;
}