An imperative API on top of promise, with cancellation support
npm install awesome-imperative-promise
Offer an imperative API on top of promise, with cancellation support
``bash`
npm install --save awesome-imperative-promise
// or
yarn add awesome-imperative-promise
- Imperative methods to trigger promise resolve/reject
- Imperative method to trigger promise cancellation (the promise will never resolve/reject)
- Can wrap an existing promise or simply create a new one
- Typescript native support
`js
import { createImperativePromise } from "awesome-imperative-promise";
const wrappedPromise = fetch("url");
// Wrap an existing promise and expose some additional imperative methods
// The existingPromise paramter is optional and the returned promise with resolve/reject when the existing promise do
const { promise, resolve, reject, cancel } = createImperativePromise(wrappedPromise);
// will make the returned promise resolved (not the wrapped one)
resolve("some value");
// will make the returned promise reject (not the wrapped one)
reject(new Error(":s"));
// will ensure the returned promise never resolves or reject
cancel();
`
The returned promise can only resolve/reject/cancel once and will ignore further imperative calls like regular promises do.
If you call cancel() and then call resolve("val")` (or if the wrapped promise resolves), the returned promise will never resolve because it has been cancelled first.
I find this useful to be able to cancel the resolution of promises, and use this lib as an implementation detail in other libs I build, like awesome-debounce-promise.
This is particularly useful in React apps where you want to ensure an async process is cancelled when component unmounts, to avoid triggering a setState and get a warning. See [isMounted() is an antipattern]
(https://reactjs.org/blog/2015/12/16/ismounted-antipattern.html)
MIT © slorber
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