Add delay to javascript method that returns promise

Question

I\'m currently trying to learn Angular 2, typescript, promises, etc. I\'ve setup a small app for developer tools and a service that just returns hard-coded data. This is to

Answer 1

Delayed native promise

New promise that resolves with undefined

return new Promise(resolve =>
  setTimeout(resolve, 5000)
);

New promise that resolves with a value

return new Promise(resolve => 
  setTimeout(() => resolve(value), 5000)
);

Existing promise

return promise.then(value => 
  new Promise(resolve => 
    setTimeout(() => resolve(value), 5000)
  )
);

Delayed Bluebird promise

Bluebird promise library has better performance and convenient features that can be used out of the box to delay promise chains.

New promise that resolves with undefined

return Bluebird.delay(5000);

New promise that resolves with a value

return Bluebird.resolve(value).delay(5000);
// or
return Bluebird.delay(5000).return(value);

Existing promise

return bluebirdPromise.delay(5000);

Delayed promise with RxJS

RxJS is already used in Angular 2/4 projects and can be used to create or transform promises with RxJS operators and small overhead.

New promise that resolves with undefined

return Observable.of().delay(5000).toPromise();
// or
return Observable.interval(5000).first().toPromise();

New promise that resolves with a value

return Observable.of(value).delay(5000).toPromise();

Existing promise

return Observable.fromPromise(promise).delay(5000).toPromise();