Promise.prototype.catch()

The catch() method of Promise instances schedules a function to be called when the promise is rejected. It immediately returns another Promise object, allowing you to chain calls to other promise methods. It is a shortcut for then(undefined, onRejected).

The catch method is used for error handling in promise composition. Since it returns a Promise, it can be chained in the same way as its sister method, then().

If a promise becomes rejected, and there are no rejection handlers to call (a handler can be attached through any of then(), catch(), or finally()), then the rejection event is surfaced by the host. In the browser, this results in an unhandledrejection event. If a handler is attached to a rejected promise whose rejection has already caused an unhandled rejection event, then another rejectionhandled event is fired.

Syntax example: promiseInstance.catch(onRejected)