Before you start working with a promise library, there are a number of elements you should keep in mind. Not all the implementations of a promise's implementation are created equally. They are different from one another in terms of offered utilities by API, performance, and sometimes, behavior too.
A promise/proposal just outlines the proposed behavior of the promises and not implementation specifications. This results in varying libraries offering a different set of features. These are the ways that they differ from one another:
- All promises/compliments have
then(); function and also have varying features in their API. In addition to this, they're still able to exchange promises with each other. - In promise/compliant libraries, a thrown exception is translated into a rejection and the
errorHandler()method is called with the exception.
As a result of the differing implementations, there are interoperability problems when working with libraries that return or expect promise/compliant.
There may be trade-offs in choosing a promise library. Every library has its own pros and cons, and it is purely up to you to decide what to use depending on the particular use case and your project needs.