up.network up:request:load

DOM event

This event is emitted before an AJAX request is sent over the network.

Only requests that are sent via Unpoly features (like [up-follow] or up.request()) will trigger this event. When making a requests using fetch() or XMLHttpRequest, no event is emitted.

The event is emitted on the layer that caused the request.

Changing requests before loading

Listeners to up:request:load can inspect or mutate the request options before it is loaded.

For example, this listeners changes requests to /stocks to include a custom header and have a timeout of 10 seconds:

up.on('up:request:load', (event) => {
  if (event.request.url === '/stocks') {
    event.request.headers['X-Client-Time'] = Date.now().toString()
    event.request.timeout = 10_000
  }
})