Fetch

A fetch call has two parts:

• JavaScript thread (data):

  • The onFulfilled[] array (queue) stores the handlers attached to the promise.
  • The onRejection[] array (queue) also stores the handlers attached to the promise.
  • When the promise settles, the resolved or rejected value is stored and each handler in the queue is called with that value.

• Web browser/Node:

  • Makes the network request.
  • If we get a response from this request, it always goes into the onFulfilled array (even HTTP errors go to this array).
  • So, fetch only rejects on a network-level failure, not on a bad HTTP status code.