@data-slot/collapsible

Headless collapsible (show/hide) component for vanilla JavaScript. Accessible, unstyled, tiny.

Installation

npm install @data-slot/collapsible

Quick Start

<div data-slot="collapsible">
  <button data-slot="collapsible-trigger">Toggle Content</button>
  <div data-slot="collapsible-content" hidden>
    Hidden content revealed on click.
  </div>
</div>

<script type="module">
  import { create } from "@data-slot/collapsible";
  
  const controllers = create();
</script>

API

Initialization

create(scope?)

Auto-discover and bind all collapsible instances in a scope (defaults to document).

import { create } from "@data-slot/collapsible";

const controllers = create(); // Returns CollapsibleController[]

createCollapsible(root, options?)

Create a controller for a specific element.

import { createCollapsible } from "@data-slot/collapsible";

const collapsible = createCollapsible(element, {
  defaultOpen: false,
  hiddenUntilFound: false,
  closeOnEscape: false,
  closeOnClickOutside: false,
  onOpenChange: (open) => console.log(open),
});

Slots

Runtime Slots

• collapsible - Root element that manages the open state.
• collapsible-trigger - Required button that toggles the content and receives aria-expanded.
• collapsible-content - Required panel that is shown or hidden with the open state.

Markup

<div data-slot="collapsible">
  <button data-slot="collapsible-trigger">Toggle</button>
  <div data-slot="collapsible-content">Content</div>
</div>

Data Attributes

Options can also be set via data attributes on the root element. JS options take precedence.

Boolean attributes: present or "true" = true, "false" = false, absent = default.

<!-- Start expanded -->
<div data-slot="collapsible" data-default-open>
  ...
</div>

Options

Controller

Events

Outbound Events

Listen for changes via custom events:

element.addEventListener("collapsible:change", (e) => {
  console.log("Collapsible open:", e.detail.open);
});

Inbound Events

Control the collapsible via events:

// Open the collapsible
element.dispatchEvent(
  new CustomEvent("collapsible:set", { detail: { open: true } })
);

// Close the collapsible
element.dispatchEvent(
  new CustomEvent("collapsible:set", { detail: { open: false } })
);

Note: Blocked when trigger is disabled (has disabled attribute or aria-disabled="true").

Deprecated Shapes

The following shape is deprecated and will be removed in v1.0:

// Deprecated: { value: boolean }
element.dispatchEvent(
  new CustomEvent("collapsible:set", { detail: { value: true } })
);

Use { open: boolean } instead.

Styling

Use data-state attributes for CSS styling (available on both root and content):

/* Hidden state */
[data-slot="collapsible-content"][hidden] {
  display: none;
}

/* Or use data-state */
[data-slot="collapsible"][data-state="closed"] [data-slot="collapsible-content"] {
  display: none;
}

/* Animate using data-state on content */
[data-slot="collapsible-content"] {
  overflow: hidden;
  transition: max-height 0.3s;
  max-height: 0;
}

[data-slot="collapsible-content"][data-state="open"] {
  max-height: 500px;
}

/* Presence lifecycle markers */
[data-slot="collapsible-content"][data-starting-style] {
  opacity: 0;
}

[data-slot="collapsible-content"][data-ending-style] {
  opacity: 0;
}

CSS Variables

The content element exposes size variables you can use for dimension animations:

Example:

[data-slot="collapsible-content"] {
  overflow: hidden;
  height: var(--collapsible-panel-height);
  width: var(--collapsible-panel-width);
  transition: height 0.25s ease, width 0.25s ease, opacity 0.2s ease;
}

[data-slot="collapsible-content"][data-starting-style],
[data-slot="collapsible-content"][data-ending-style] {
  height: 0;
  opacity: 0;
}

Accessibility

The component automatically handles:

• aria-expanded state on trigger
• aria-controls linking trigger to content
• role="region" on content
• aria-labelledby linking content back to trigger
• Unique ID generation for trigger and content
• Disabled trigger support (respects disabled attribute and aria-disabled="true")
• Focus returns to the trigger when Escape closes the collapsible while focus is inside it

Behavior

Dismissal

Collapsibles stay open until toggled by default. Enable closeOnEscape and closeOnClickOutside (or data-close-on-escape and data-close-on-click-outside) for disclosures that behave like a light-dismiss layer, such as a mobile navigation panel.

<div data-slot="collapsible" data-close-on-escape data-close-on-click-outside>
  <button data-slot="collapsible-trigger">Menu</button>
  <nav data-slot="collapsible-content" aria-label="Main">...</nav>
</div>

Dismissal uses the same layer stack as popovers, dialogs and menus:

• Escape closes only the most recently opened layer, so a popover inside the panel closes first.
• Presses inside portaled descendants, such as a popover opened from the panel, count as inside.
• On touch devices, an outside press closes the panel on click, so scrolling the page does not dismiss it.
• Dismissal is blocked while the trigger is disabled.

Find-in-Page Support

Enable hiddenUntilFound (or data-hidden-until-found) to close panels with hidden="until-found". This allows browser find-in-page to reveal matching text.

With Tailwind:

<div data-slot="collapsible" class="group">
  <button data-slot="collapsible-trigger" class="flex items-center gap-2">
    <span>Show more</span>
    <svg class="group-data-[state=open]:rotate-180 transition-transform">...</svg>
  </button>
  <div data-slot="collapsible-content" class="hidden group-data-[state=open]:block">
    Content here
  </div>
</div>

License

MIT