PubSub/A is an interface for libraries implementing the Publish/Subscribe pattern (also often referred to as Observer pattern). The aim of PubSub/A is to provide a unified, asynchronous common API for pubsub (similiar to the Promise/A proposal that defined a unified API for promises).

PubSub/A uses the so-called topic-based Publish/Subscribe with the additional concept of channels for grouping together topics.

A reference implementation written in TypeScript (but usable from plain JavaScript) is available here.

const pubsub = new PubSubImplementation();

// channels are initialized asynchronously, provide a way to namespace topics
pubsub.channel('mychannel').then(channel => {

    // subscribe
    channel.subscribe('myTopic', arg => {
        console.log('I received a notification: ' + arg.message);
    })M

    // publish - you can pass any custom object as argument
    channel.publish('myTopic', { message: 'Hello world!' });
});

The specification is included in the SPECIFICIATION.md file. The interface definitions in this project are written as TypeScript interfaces to provide a statically typed API for better understanding. As this project only includes interfaces and not actual implementations, the resulting output from the TypeScript compiler is an empty JavaScript file.

• pubsub-micro - A reference implementation written in TypeScript but usable from any JavaScript project

An official test suite is available to test your implementation for validity.

MIT.