Form submission #155

Summary#

Implement HTML form submission: collecting form data, encoding it, and sending the HTTP request.

Details#

Submit triggers#

• Click on `<input type="submit">` or `<button type="submit">`
• Press Enter in a single-line text input
• Call `form.submit()` from JavaScript (bypasses validation)
• Call `form.requestSubmit()` from JavaScript (runs validation first)

Submit algorithm#

1. Determine submitter element
2. Run constraint validation (unless `novalidate` attribute on form or `formnovalidate` on submitter)
3. If validation fails, fire `invalid` events, abort submission
4. Construct entry list from form's submittable elements:
   • Include name/value pairs for enabled, named controls
   • Skip disabled controls, unchecked checkboxes/radios, unselected file inputs
   • For select: include value of each selected option
   • For textarea: include current text value
5. Fire `submit` event (cancelable)
6. Encode entry list based on `enctype`
7. Navigate using `action` URL, `method`, and encoded data

Encoding types#

• `application/x-www-form-urlencoded` (default): percent-encode name=value pairs joined with &
• `multipart/form-data`: MIME multipart encoding with boundary
• `text/plain`: name=value pairs separated by newlines

Form attributes#

• `action`: target URL (default: current page URL)
• `method`: GET or POST (default: GET)
• `enctype`: encoding type
• `target`: browsing context for response (_self, _blank, etc.)
• Submitter overrides: `formaction`, `formmethod`, `formenctype`, `formtarget`
• `novalidate` / `formnovalidate`: skip validation

GET vs POST#

• GET: append encoded data as URL query string, navigate
• POST: send encoded data as request body via net crate

Acceptance criteria#

• Submit button click and Enter key trigger form submission
• Constraint validation runs before submission (unless novalidate)
• Entry list correctly collects name/value pairs from all control types
• `application/x-www-form-urlencoded` encoding works correctly
• `multipart/form-data` encoding works correctly
• GET submission appends query string to action URL
• POST submission sends request body with correct Content-Type
• `submit` event fires and is cancelable
• `form.submit()` and `form.requestSubmit()` work correctly
• Submitter attribute overrides (`formaction`, etc.) are respected
• Tests cover entry list construction, both encoding types, GET/POST, and validation integration

Dependencies#

• Form element parsing and DOM interfaces
• Text editing: cursor, selection, and keyboard input
• HTML5 constraint validation