Creating Promise wrappers with Promise.resolve() and Promise.reject()

It is useful to have the ability to create promise objects that have already reached a final state with a defined value, and also to be able to normalize JavaScript objects into promises. Promise.resolve() and Promise.reject() afford you the ability to perform both these actions.

Note

The code, links, and a live example of this are available at http://ngcookbook.herokuapp.com/9315/ .

How to do it...

Like all other static Promise methods, Promise.resolve() and Promise.reject() return a promise object. In this case, there is no executor definition.

If one of these methods is provided with a non-promise argument, the returned promise will assume either a fulfilled or rejected state (corresponding to the invoked method). This method will pass the argument to Promise.resolve() and Promise.reject(), along with any corresponding handlers:

Promise.resolve('foo'); 
// Promise {[[PromiseStatus]]: "resolved", [[PromiseValue]]: "foo...