https://github.com/cameronhunter/pending-promises

A map of pending promises that can be resolved/rejected at a later time.
https://github.com/cameronhunter/pending-promises

Last synced: 8 months ago
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A map of pending promises that can be resolved/rejected at a later time.

• Host: GitHub
• URL: https://github.com/cameronhunter/pending-promises
• Owner: cameronhunter
• Created: 2023-11-19T00:12:14.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2024-02-19T01:54:47.000Z (over 2 years ago)
• Last Synced: 2025-02-07T05:49:33.462Z (over 1 year ago)
• Language: TypeScript
• Size: 327 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 5
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md

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README

          
# `@cameronhunter/pending-promises`

[![npm package](https://img.shields.io/npm/v/%40cameronhunter/pending-promises?logo=npm)](https://www.npmjs.com/package/@cameronhunter/pending-promises)

[![npm downloads](https://img.shields.io/npm/dm/%40cameronhunter/pending-promises?logo=npm)](https://www.npmjs.com/package/@cameronhunter/pending-promises)

[![main branch status](https://img.shields.io/github/actions/workflow/status/cameronhunter/pending-promises/post-merge.yml?logo=github&label=main)](https://github.com/cameronhunter/pending-promises/actions/workflows/post-merge.yml)

> A map of pending promises that can be resolved/rejected at a later time.

This data structure helps convert event-based APIs to promise-based. Here's an

example that wraps a WebSocket client, providing a promise-based API.

```ts

import { PendingPromises } from '@cameronhunter/pending-promises';

class MyAPI {

    readonly #responses: PendingPromises = new PendingPromises();

    readonly #ws: WebSocket;

    constructor(ws: WebSocket) {

        this.#ws = ws;

        this.#ws.on('message', this.#onMessage.bind(this));

    }

    send(message: string): Promise {

        // Create a new pending promise

        const [id, promise] = this.#responses.create();

        ws.send(JSON.stringify({ id, message }), (err) => {

            if (err) {

                // Reject immediately if sending fails.

                this.#responses.reject(id, err);

            }

        });

        return promise;

    }

    #onMessage(event: WebSocket.MessageEvent): void {

        const { id, result, error } = JSON.parse(event.data as string);

        if (id) {

            if (error) {

                this.#responses.reject(id, error);

            } else {

                this.#responses.resolve(id, result);

            }

        }

    }

}

```