Adding a JavaScript class when clicking a link

Question

I have the following links:

<a class="active" href="#section1">Link 1</a> 
<a href="#section2">Link 2</a>

When I click on link 2, I would like it to get the active class and remove the class from link 1 itself, so that it really becomes:

<a href="#section1">Link 1</a> 
<a class="active" href="#section2">Link 2</a>

This should work both ways. I.e. any click on the link gets the class and removes it from another.

How can this be done using JavaScript / Prototype?

Answer 1

You can write a small helper function using prototype support, which removes the class from all elements activeand adds it to the one you clicked on:

function active(e) {
    $$('.active').each(function(i) {
        i.removeClassName('active');
    });
    e.addClassName('active');
};

You can call this function from events onclick:

<a href="#sectiona" onclick="active(this)">a</a>
<a href="#sectionb" onclick="active(this)">b</a>
<a href="#sectionc" onclick="active(this)">c</a>

Answer 2

Try the following:

// initialization
var links = document.links;
for (var i=0; i<links.length; ++i) {
    links[i].onclick = function() {
        setActive(links, this);
    };
}

function setActive(links, activeLink) {
    for (var i=0; i<links.length; ++i) {
        var currentLink = links[i];
        if (currentLink === activeLink) {
            currentLink.className += " active";
        } else {
            currentLink.className = currentLink.className.split(/\s+/).map(function(val) {
                return val === "active" ? "" : val;
            }).join(" ");
        }
    }
}

Answer 3

If it were jQuery, I would do it like

   $(document).ready(
     function(){
       $("a").click(function(){
         $("a").toggleClass("active");
       });
     }
   )