Available since v0.1.0

Fires on the native submit event — place it on the <form> element. A capture-phase listener means the agent sees the submit even if a framework or library calls preventDefault() later (HTMX, for instance, suppresses the native submit after its listeners run).

Syntax

<form
  fs-assert="contact/submit-form"
  fs-trigger="submit"
  fs-assert-visible=".success-message">
  <input name="email" type="email" />
  <button type="submit">Send</button>
</form>

When to use it

• Form submissions — the canonical choice over click on the submit button
• Any <form> whose submit semantics matter for correctness

Either fs-trigger="submit" on the form OR fs-trigger="click" on the submit button works. Pick the one that reads clearer for your markup. Don't use both on the same assertion key — you'll get two fires per submit.

Example

<form
  fs-assert="signup/create-account"
  fs-trigger="submit"
  fs-assert-mutex="each"
  fs-assert-visible-success=".welcome-dashboard"
  fs-assert-added-error=".form-errors">
  …
</form>

Pairs well with

• Conditional assertions — success / validation-error / server-error branches
• fs-assert-mutex="each" — group cross-type conditionals
• fs-assert-timeout — network operations deserve an explicit SLA
• fs-assert-mpa="true" — persist the assertion across a full page navigation

Gotchas

• Enter-to-submit bypasses the submit button. If you put the trigger on the button instead of the form, pressing Enter inside a text field submits the form without firing the click handler. Prefer submit on the form to cover both paths.
• AJAX submits via preventDefault. Capture listeners see the event first, so the assertion still fires even when JS prevents the real submission.

See also

• click — alternative placement on the submit button
• Patterns cookbook #6
• Triggers index