How to add “active” class to current menu item in WordPress

Question

I have a WordPress based website, and my theme highlights the current menu item by adding "current-menu-item" class to it.

The thing is that I have a menu item with 3 submenu items and all of them point to the same page with different container ids (their href contains container Id), hence all of them are highlighted.

How can I highlight only the menu item which's href points to the currently viewed container?

<ul>
<li><ahref="URL/who-we-are/"><span>WhoWeAre</span></a>
<ul>
    <li id="first"><ahref="URL/who-we-are/#wherewework"><span>WhereWeWork</span></a></li>
    <li id="second"><ahref="URL/who-we-are/#whatwebelieve"><span>WhatWeBelieve</span></a></li>
    <li id="third"><ahref="URL/who-we-are/#ourpartners"><span>OurPartners</span></a></li>
</ul>
</li>
<li><ahref="#"><span>GetInvolved</span></a>
<ul>
    <li><ahref="URL/vacancies/"><span>Vacancies</span></a></li>
    <li><ahref="URL/Become-Active/"><span>BecomeActive</span></a></li>
</ul>
</li>
<li><ahref="URL/contactus/"><span>ContactUs</span></a></li>
</ul>

I have tried this answer by inserting the following after tag:

function onVisibilityChange(el, callback) {
    var old_visible;
    return function () {
        var visible = isElementInViewport(el);
        if (visible != old_visible) {
            old_visible = visible;
            if (typeof callback == 'function') {
                callback();
            }
        }
    }
}

var handler = onVisibilityChange(#whatwebelieve, function() {
    $( "#second" ).removeClass( "current-menu-item" )
});


//jQuery
$(window).on('DOMContentLoaded load resize scroll', handler);

Answer 1

It a simple scrollspy.

// Cache selectors
var lastId,
  topMenu = $("#top-menu"),
  topMenuHeight = topMenu.outerHeight() + 15,
  // All list items
  menuItems = topMenu.find("a"),
  // Anchors corresponding to menu items
  scrollItems = menuItems.map(function() {
    var item = $($(this).attr("href"));
    if (item.length) {
      return item;
    }
  });

// Bind click handler to menu items
// so we can get a fancy scroll animation
menuItems.click(function(e) {
  var href = $(this).attr("href"),
    offsetTop = href === "#" ? 0 : $(href).offset().top - topMenuHeight + 1;
  $('html, body').stop().animate({
    scrollTop: offsetTop
  }, 300);
  e.preventDefault();
});

// Bind to scroll
$(window).scroll(function() {
  // Get container scroll position
  var fromTop = $(this).scrollTop() + topMenuHeight;

  // Get id of current scroll item
  var cur = scrollItems.map(function() {
    if ($(this).offset().top < fromTop)
      return this;
  });
  // Get the id of the current element
  cur = cur[cur.length - 1];
  var id = cur && cur.length ? cur[0].id : "";

  if (lastId !== id) {
    lastId = id;
    // Set/remove active class
    menuItems
      .parent().removeClass("active")
      .end().filter("[href='#" + id + "']").parent().addClass("active");
  }
});

body {
  height: 6000px;
  font-family: Helvetica, Arial;
}

#top-menu {
  position: fixed;
  z-index: 1;
  background: white;
  left: 0;
  right: 0;
  top: 0;
}

#top-menu li {
  float: left;
}

#top-menu a {
  display: block;
  padding: 5px 25px 7px 25px;
  width: 4em;
  text-align: center;
  -webkit-transition: .5s all ease-out;
  -moz-transition: .5s all ease-out;
  transition: .5s all ease-out;
  border-top: 3px solid white;
  color: #aaa;
  text-decoration: none;
}

#top-menu a:hover {
  color: #000;
}

#top-menu li.active a {
  border-top: 3px solid #333;
  color: #333;
}

#foo {
  position: absolute;
  top: 400px;
}

#bar {
  position: absolute;
  top: 800px;
}

#baz {
  position: absolute;
  top: 1200px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul id="top-menu">
  <li class="active">
    <a href="#">Top</a>
  </li>
  <li>
    <a href="#foo">Foo</a>
  </li>
  <li>
    <a href="#bar">Bar</a>
  </li>
  <li>
    <a href="#baz">Baz</a>
  </li>
</ul>

<a id="foo">Foo</a>


<a id="bar">Bar</a>


<a id="baz">Baz</a>