Examples of using Rejection handler in English and their translations into Bulgarian
{-}
-
Colloquial
-
Official
-
Medicine
-
Ecclesiastic
-
Ecclesiastic
-
Computer
Rejection handlers work the same way.
You could, however, attach a rejection handler instead.
When a rejection handler is called, it may return a value.
That value is then passed to the rejection handler for p1.
Here, the rejection handler is called as a result of p2 being rejected.
Here, the rejectionHandled event is emitted when the rejection handler is finally called.
In this case, the rejection handler is passed 43 to reflect the rejection from p2.
If an error is thrown inside an executor,then the promise's rejection handler is called.
That value is passed into the rejection handler for the promise, where value+ 1 is returned.
Promises also have a catch() method that behaves the same as then()when only a rejection handler is passed.
Just know that if you don't attach a rejection handler to a promise, all failures will happen silently.
That handler then throws another error that is caught by the second promise's rejection handler.
This allows you to add new fulfillment and rejection handlers at any time and guarantee that they will be called.
The chained call to the catch() method, which is on a second promise,is able to receive that error through its rejection handler.
Returning thenables from fulfillment or rejection handlers doesn't change when the promise executors are executed.
The rejection handler would instead be called during the same turn of the event loop where rejected was created, which isn't useful.
RejectionHandled: Emitted when a promise is rejected and a rejection handler is called after one turn of the event loop.
A fulfillment or rejection handler will still be executed even if it is added to the job queue after the promise is already settled.
UnhandledRejection: Emitted when a promise is rejected and no rejection handler is called within one turn of the event loop.
One of the most controversial aspects of promises is the silent failure that occurs when a promise is rejected without a rejection handler.
If p2 were rejected, a rejection handler(if present) would be called instead of the second fulfillment handler. .
Promise chaining allows you to catch errors that may occur in a fulfillment or rejection handler from a previous promise.
That's because fulfillment and rejection handlers are always added to the end of the job queue after the executor has completed.
The executor handles catching any thrown errors to simplify this common use case, butan error thrown in the executor is only reported when a rejection handler is present.
Always have a rejection handler at the end of a promise chain to ensure that you can properly handle any errors that may occur.
If a built-in promise is passed to either method, the promise will be resolved or rejected, andthe method will return a new MyPromise so you can assign fulfillment and rejection handlers.
Returning primitive values from fulfillment and rejection handlers allows passing of data between promises, but what if you return an object?
The rejection handler always receives a single value rather than an array, and the value is the rejection value from the promise that was rejected.
The then() method allows you to assign a fulfillment and rejection handler and the catch()method allows you to assign only a rejection handler.
The rejection handler for p4 is called immediately without waiting for p1 or p3 to finish executing(They do still finish executing; p4 just doesn't wait.).