Deprecated

All reasonably modern platforms support native Promises, so this library is obsolete. Use the native Promise API instead.

promise-ponyfill

Preconfigured Promise ponyfill based on promise-polyfill and setasap.

A ponyfill is like a polyfill, but it does not alter the global namespace.

Why?

This ponyfill is based on promise-polyfill. Out of the box promise-polyfill implements Promise using setImmediate if available, and otherwise it falls back to setTimeout.

This leads to a significant performance degradation on platforms where neither Promise nor setImmediate are available natively. For optimal performance on these platforms it is necessary to configure promise-polyfill to use a setImmediate polyfill such as setasap.

This module preconfigures promise-polyfill to use setasap so you don't have to think about it. Just import this module and use it like a regular Promise.

Installation and usage

npm install --save promise-ponyfill

import Promise from "promise-ponyfill";

const promise = new Promise((resolve, reject) =>
                            setTimeout(resolve, 1000));

promise.then(value => console.log("Promise resolved."))
    .catch(reason => console.error("Promise rejected", reason));

If the platform provides a native implementation of Promise, then this module will simply return the native implementation.

This is a wilful violation of the usual philosophy of ponyfills, which advocate returning the polyfill implementation in all cases. I believe that this is the best choice in this case because native Promise provides better error reporting, and I am not aware of any platforms that provide a bad native Promise implementation. If you are aware of any please let me know by raising an issue.

Copyright

See LICENSE.md for copyright and licensing information pertaining to this module.

promise-polyfill and setasap have their own separate copyright and licensing terms. See the documentation for those modules.