The details element

The details element is one of my favorite HTML elements. Yes, I have favorite HTML elements. Yes, I know that's weird.

The Disclosure pattern

So, what does this wonderful element do? Out of the box, it's a way to natively achieve the disclosure pattern.

The disclosure pattern involves some content and a button (the summary element) that controls the visibility of that content. When the content is hidden, the button shows the content. When the content is shown, the button hides the content.

Previously this was something that you could only do with JavaScript. And while it wasn't difficult to do, I love when I can replace JavaScript with a native element that Just Works.™

What's it good for?

details is a perfect fit for FAQs. You don't even have to do that much extra styling.

And even though details isn't a native accordion element (personally, I would rather have a tabs element), it goes a long way toward a nicer progressive enhancement experience:

Just bear in mind that you'll need to add some extra ARIA roles and keyboard support on top of the default element.

Menus

One particular type of use for details is really why I'm so fascinated with them. GitHub has implemented a pattern to use the element for their menus. It's pretty ingenious.

My favorite part of their implementation is adding a pseudo-element to the summary element that covers the entire screen. This elegantly closes the menu with an outside click:

[open] > summary:before {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 80;
    display: block;
    cursor: default;
    content: " ";
    background: transparent;
}

.details-menu {
    position: absolute;
    top: 100%;
    left: 0;
    z-index: 100;
    /* more specific styles...*/
}

Gotchas

Of course, it wouldn't be the web if it didn't have any gotchas. First, [summary styling](https://css-tricks.com/quick-reminder-that-details-summary-is-the-easiest-way-ever-to-make-an-accordion/) is a bit inconsistent across browsers, but nowhere near as weird as other elements.

Second, summarys can include a single heading element (h1–6), but because it natively carries the implicit ARIA role of button, any children, including headings, will be stripped of their semantic role. Depending on what's used, certain screen reader and browser combinations may not recognize heading children or allow them to be used for navigation.

Finally, there is no support in Internet Explorer, which is becoming less and less of a problem every day. There is a polyfill, but I would simply let the content display completely. Unless it's absolutely necessary, sending more JavaScript to less capable browsers just for consistency's sake doesn't make much sense to me.

Semantics for the win

So, details provides a simple, semantic way to implement the common disclosure pattern. Its flexibility and availability make it a powerful addition to any frontend developer's arsenal.

Do you have a favorite HTML element? I would love to hear about it. And if you're reading on Dev Community, please consider liking this post and sharing it with others. It makes me feel all warm inside and stuff.

Till next time!