up.fragment up:fragment:keep

DOM event

This event is emitted before an existing element is kept during a render pass.

Event listeners can call event.preventDefault() on an up:fragment:keep event to prevent the element from being persisted. If the event is prevented, the element will be replaced with a fragment from the response.

Preserving elements

Example

The following would only keep an <audio up-keep> element as long as it plays the same song (as identified by the tag's src attribute):

up.on('up:fragment:keep', 'audio', function(event) {
  if (element.getAttribute('src') !== event.newElement.getAttribute('src')) {
    // Preventing the event forces an update
    event.preventDefault()
  }
})

You may also define an up:fragment:keep listener in HTML using an [up-on-keep] attribute.