up.fragment up:fragment:loaded

DOM event

This event is emitted when the server responds with the HTML, before the HTML is used to change a fragment.

Event listeners may call event.preventDefault() on an up:fragment:loaded event to prevent any changes to the DOM and browser history. This is useful to detect an entirely different page layout (like a maintenance page or fatal server error) which should be open with a full page load:

up.on('up:fragment:loaded', (event) => {
  let isMaintenancePage = event.response.getHeader('X-Maintenance')

  if (isMaintenancePage) {
    // Prevent the fragment update and don't update browser history
    event.preventDefault()

    // Make a full page load for the same request.
    event.request.loadPage()
  }
})

Instead of preventing the update, listeners may also access the event.renderOptions object to mutate options to the up.render() call that will process the server response.