Jon Staab
41 lines
1.1 KiB
Markdown
41 lines
1.1 KiB
Markdown
# Deferred Promises
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The `Deferred` module provides utilities for creating promises with exposed resolve/reject functions and typed error handling. This is particularly useful for managing asynchronous operations where you need external control over promise resolution.
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## API
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```typescript
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// Creates a Deferred promise
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export declare const defer: <T, E = T>() => Deferred<T, E>;
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// Promise with exposed resolve/reject functions and typed error
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export type Deferred<T, E = T> = CustomPromise<T, E> & {
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resolve: (arg: T) => void;
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reject: (arg: E) => void;
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};
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// Creates a Promise with strongly typed error
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export declare function makePromise<T, E>(
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executor: (resolve: (value: T | PromiseLike<T>) => void, reject: (reason: E) => void) => void,
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): CustomPromise<T, E>;
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```
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## Example
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```typescript
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import { defer } from '@welshman/lib';
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// Create a deferred promise
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const deferred = defer<string>();
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// Resolve it externally
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setTimeout(() => {
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deferred.resolve('Hello, world!');
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}, 1000);
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// Use it like a regular promise
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deferred.then(value => {
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console.log(value); // "Hello, world!"
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});
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```
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