Promise.prototype

The Promise.prototype property represents the prototype for the Promise constructor.

Description

Promise instances inherit from Promise.prototype. You can use the constructor's prototype object to add properties or methods to all Promise instances.

Properties

Promise.prototype.constructor

Returns the function that created an instance's prototype. This is the Promise function by default.

Methods

Promise.prototype.catch(onRejected)

Appends a rejection handler callback to the promise, and returns a new promise resolving to the return value of the callback if it is called, or to its original fulfillment value if the promise is instead fulfilled.

Promise.prototype.then(onFulfilled, onRejected)

Appends fulfillment and rejection handlers to the promise, and returns a new promise resolving to the return value of the called handler, or to its original settled value if the promise was not handled (i.e. if the relevant handler onFulfilled or onRejected is not a function).

Promise.prototype.finally(onFinally)

Appends a handler to the promise, and returns a new promise which is resolved when the original promise is resolved. The handler is called when the promise is settled, whether fulfilled or rejected.

Specifications

Browser compatibility

See also

• Promise