`Expander`¶

Reveal optional content with native details/summary behavior.


Import	`from hedron import Expander`
Distribution	`hedron`
Backend activity	No
Normal render mode	`RenderMode.FRAGMENT`

Live demo¶

Advanced settings

Configure retry and timeout behavior.

The preview is a local docs simulation (not a running Hedron server). Interactive demos show a “Simulated HTMX” trace when applicable.

Basic use¶

from hedron import Expander, Text

component = Expander('Advanced settings', Text('Configure retry and timeout behavior.'))

Compose under Page for full documents, or return from a fragment route for HTMX swaps.

How it works¶

The native details element supplies keyboard and disclosure state without custom JavaScript. Content remains in the document and participates in search.

This component's core behavior is server-rendered HTML and does not require a browser runtime. The preview is ordinary semantic HTML, so keyboard, form, link, and disclosure behavior comes from the platform.

Constructor and parameters¶

Expander(title, *nodes, children=None, open=False, id=None, class_=None)

Parameter	Type	Meaning
`title`	`str`	Visible summary label.
`nodes`	`NodeLike`	Positional disclosure content.
`children`	`NodeLike \| sequence \| None`	Keyword disclosure content; combines with positional nodes.
`open`	`bool`	Initial expanded state.
`id`	`str \| None`	Stable ID for links, tests, or replacement.
`class_`	`str \| None`	Application class appended to `hedron-expander`.

Composition and backend behavior¶

Keep Expander at the smallest semantic boundary. Fragment routes should return only the replaced region and preserve stable target IDs across success, validation, empty, loading, and error responses.

This component is primarily presentational; keep any mutation on an explicit action or component route.

Accessibility¶

Use a summary that describes the hidden content, not a generic “More”.

Security¶

Escaping and SafeUrl / TrustedHtml are framework concerns; authorization and data exposure remain application code. Redact secrets before rendering.

Common mistakes¶

Do not hide required fields or primary instructions in a collapsed expander.
Do not copy docs-preview JavaScript into an application server.

Testing¶

from hedron import RenderMode, render

result = render(component, mode=RenderMode.FRAGMENT)
assert result.html
assert not result.diagnostics

All component demos · Built-in API · Testing

Expander¶