NavigateEvent: formData property

Baseline 2026

Newly available

Since January 2026, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

The formData read-only property of the NavigateEvent interface returns the FormData object representing the submitted data in the case of a POST form submission, or null otherwise.

Value

A FormData object, or null.

Examples

navigation.addEventListener("navigate", (event) => {
  // Some navigations, e.g. cross-origin navigations, we
  // cannot intercept. Let the browser handle those normally.
  if (!event.canIntercept) {
    return;
  }

  // Don't intercept fragment navigations or downloads.
  if (event.hashChange || event.downloadRequest !== null) {
    return;
  }

  event.intercept({
    handler() {
      if (event.formData) {
        processFormDataAndUpdateUI(event.formData, event.signal);
      } else {
        doSinglePageAppNav(event.destination, event.signal);
      }
    },
  });
});