kevinokerlund / cancellable-promise

An extension of native ES6 Promises that provides the ability to cancel and/or clear promise chains.

cancellable-promise

An extension of native ES6 Promises that provides the ability to cancel and clear promise chains.

Usage

Creating a new cancellable promise

Cancellable promises are created just like regular promises, the only difference is the constructor you use.

let promise = new CancellablePromise((resolve, reject) => {
	setTimeout(() => {
		resolve('Resolved!');
	}, 500)
});

promise
    .then(val => console.log(val))
    .catch(val => console.log(val));

Cancelling a promise

Cancelling a promise, internally calls the "reject" on the promise.

promise.cancel();

Clearing a promise chain

Sometimes it is helpful to just clear all the .then, and .catch promise chains. This method clears whatever has been set in the past.

promise.clear();

Common questions

Will a cancellable promise still work with Promise.race, and Promise.all?

Yes. This extension literally extends Promise.

When I call cancel on a promise, will it cause an error in the browser?

.cancel internally calls the rejection callback and so it will default to however the browser treats a rejected promise for ES6. Chrome for example will throw an error if a rejection is called on a promise, and there is no .catch. Firefox and Safari on the other hand, will not.