Adding open/closed icon to Twitter Bootstrap collapsibles (accordions)

Here it's the answer for those who are looking for a solution in Bootstrap 3(like myself).

The HTML part:

<div class="btn-group">
  <button type="button" class="btn btn-danger">Action</button>
  <button type="button" class="btn btn-danger" data-toggle="collapse" data-target="#demo">
    <span class="glyphicon glyphicon-minus"></span>
  </button>
</div>
<div id="demo" class="collapse in">Some dummy text in here.</div>

The js part:

$('.collapse').on('shown.bs.collapse', function(){
$(this).parent().find(".glyphicon-plus").removeClass("glyphicon-plus").addClass("glyphicon-minus");
}).on('hidden.bs.collapse', function(){
$(this).parent().find(".glyphicon-minus").removeClass("glyphicon-minus").addClass("glyphicon-plus");
});

---

Example accordion:

Bootply accordion example

The Bootstrap Collapse has some Events that you can react to:

$(document).ready(function(){    
    $('#accordProfile').on('shown', function () {
       $(".icon-chevron-down").removeClass("icon-chevron-down").addClass("icon-chevron-up");
    });

    $('#accordProfile').on('hidden', function () {
       $(".icon-chevron-up").removeClass("icon-chevron-up").addClass("icon-chevron-down");
    });
});

Here is my approach for Bootstrap 2.x. It is just some css. No JavaScript needed:

    .accordion-caret .accordion-toggle:hover {
        text-decoration: none;
    }
    .accordion-caret .accordion-toggle:hover span,
    .accordion-caret .accordion-toggle:hover strong {
        text-decoration: underline;
    }
    .accordion-caret .accordion-toggle:before {
        font-size: 25px;
        vertical-align: -3px;
    }
    .accordion-caret .accordion-toggle:not(.collapsed):before {
        content: "▾";
        margin-right: 0px;
    }
    .accordion-caret .accordion-toggle.collapsed:before {
        content: "▸";
        margin-right: 0px;
    }

Just add class accordion-caret to the accordion-group div, like this:

<div class="accordion-group accordion-caret">
    <div class="accordion-heading">
        <a class="accordion-toggle" data-toggle="collapse" href="#collapseOne">
            <strong>Header</strong>
        </a>
    </div>
    <div id="collapseOne" class="accordion-body collapse in">
        <div class="accordion-inner">
            Content
        </div>
    </div>
</div>

Use CSSes pseudo-selector :after using Bootstrap 3's integrated Glyphicons for a no JS answer with minor modification to your HTML...

CSS

.panel-heading [data-toggle="collapse"]:after
{
    font-family: 'Glyphicons Halflings';
    content: "\e072"; /* "play" icon */
    float: right;
    color: #b0c5d8;
    font-size: 18px;
    line-height: 22px;

    /* rotate "play" icon from > (right arrow) to down arrow */
    -webkit-transform: rotate(-90deg);
    -moz-transform:    rotate(-90deg);
    -ms-transform:     rotate(-90deg);
    -o-transform:      rotate(-90deg);
    transform:         rotate(-90deg);
}
.panel-heading [data-toggle="collapse"].collapsed:after
{
    /* rotate "play" icon from > (right arrow) to ^ (up arrow) */
    -webkit-transform: rotate(90deg);
    -moz-transform:    rotate(90deg);
    -ms-transform:     rotate(90deg);
    -o-transform:      rotate(90deg);
    transform:         rotate(90deg);
}

HTML

Add class="collapsed" to any anchor tags that are closed by default.

This will turn anchors such as

<a data-toggle="collapse" data-parent="#accordion" href="#collapseTwo">

into

<a class="collapsed" data-toggle="collapse" data-parent="#accordion" href="#collapseTwo">

CodePen Live Example

http://codepen.io/anon/pen/VYobER

Screenshot