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How To - Collapsibles/Accordion


Learn how to create an accordion (collapsible content).


Accordion

Accordions are useful when you want to toggle between hiding and showing large amount of content:

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Create An Accordion

Step 1) Add HTML:

Example

<button class="accordion">Section 1</button>
<div class="panel">
  <p>Lorem ipsum...</p>
</div>

<button class="accordion">Section 2</button>
<div class="panel">
  <p>Lorem ipsum...</p>
</div>

<button class="accordion">Section 3</button>
<div class="panel">
  <p>Lorem ipsum...</p>
</div>

Step 2) Add CSS:

Style the accordion:

Example

/* Style the buttons that are used to open and close the accordion panel */
button.accordion {
    background-color: #eee;
    color: #444;
    cursor: pointer;
    padding: 18px;
    width: 100%;
    text-align: left;
    border: none;
    outline: none;
    transition: 0.4s;
}

/* Add a background color to the button if it is clicked on (add the .active class with JS), and when you move the mouse over it (hover) */
button.accordion.active, button.accordion:hover {
    background-color: #ddd;
}

/* Style the accordion panel. Note: hidden by default */
div.panel {
    padding: 0 18px;
    background-color: white;
    display: none;
}

Step 3) Add JavaScript:

Example

var acc = document.getElementsByClassName("accordion");
var i;

for (i = 0; i < acc.length; i++) {
    acc[i].onclick = function(){
        /* Toggle between adding and removing the "active" class,
        to highlight the button that controls the panel */
        this.classList.toggle("active");

        /* Toggle between hiding and showing the active panel */
        var panel = this.nextElementSibling;
        if (panel.style.display === "block") {
            panel.style.display = "none";
        } else {
            panel.style.display = "block";
        }
    }
}
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Animated Accordion (Slide Down)

To make an animated accordion, add max-height: 0, overflow: hidden and a transition for the max-height property, to the panel class.

Then, use JavaScript to slide down the content by setting a calculated max-height, depending on the panel's height on different screen sizes:

Example

<style>
div.panel {
    padding: 0 18px;
    background-color: white;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.2s ease-out;
}
</style>

<script>
var acc = document.getElementsByClassName("accordion");
var i;

for (i = 0; i < acc.length; i++) {
  acc[i].onclick = function() {
    this.classList.toggle("active");
    var panel = this.nextElementSibling;
    if (panel.style.maxHeight){
      panel.style.maxHeight = null;
    } else {
      panel.style.maxHeight = panel.scrollHeight + "px";
    }
  }
}
</script>
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Add Icons

Add a symbol to each button to indicate whether the collapsible content is open or closed:

Example

button.accordion:after {
    content: '\02795'; /* Unicode character for "plus" sign (+) */
    font-size: 13px;
    color: #777;
    float: right;
    margin-left: 5px;
}

button.accordion.active:after {
    content: "\2796"; /* Unicode character for "minus" sign (-) */
}
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