Observables using Web Streams (JS/TS)

A catalog of Sources, Transforms, Sinks, and Combiners (a la ReactiveX) implemented using the Web Streams API (a la TransformStream) which is now native to all modern Javascript runtimes.

Background

Useful for modules that want to process data or object ReadableStreams with a more concise API, or when producing programs that want to react to multiple inbound data sources in an ordered way. Transforms from this library seamlessly interoperate with normal TransformStream implementations such as CompressionStream.

This module has no dependencies and considered feature-complete. Updates are generally only for improved compatibility with newer runtimes.

A Deno-friendly port of surma's observables-with-streams.

🚨 Breaking Change in v1.5.0

All exported modules were renamed to remove .ts extensions and /mod.ts filenames.

If you only import the default export (@cloudydeno/stream-observables) then you don't need to change anything.

Import specifier in v1.4 and earlier	Import specifier starting in v1.5
@cloudydeno/stream-observables/mod.ts	@cloudydeno/stream-observables
@cloudydeno/stream-observables/sinks/mod.ts	@cloudydeno/stream-observables/sinks
@cloudydeno/stream-observables/sinks/collect.ts	@cloudydeno/stream-observables/sinks/collect

Installation

Releases are published to jsr:@cloudydeno/stream-observables. The sidebar contains setup instructions for the common package managers. Read more about using packages.

For example, when using Deno:

deno add jsr:@cloudydeno/stream-observables

or Yarn (on nodejs):

yarn add jsr:@cloudydeno/stream-observables

Also previously published to /x/: https://deno.land/x/[email protected]/ This frozen release won't be receiving further releases.

Example Usage

import * as ows from "@cloudydeno/stream-observables";

console.log('Tap Enter to add energy!');
ows.merge(
  ows.fromTimer(1000)
    .pipeThrough(ows.map(() => -1)),
  ows.fromIterable(Deno.stdin.readable)
    .pipeThrough(ows.map(() => 1)),
)
  .pipeThrough(
    ows.scan((v0, v1) => Math.max(v0 + v1, 0), 0)
  )
  .pipeThrough(
    ows.distinct()
  )
  .pipeTo(
    ows.subscribe(
      v => console.log('Energy:', v)
    )
  );

Documentation

All exported functions are documented on JSR.

The Web Streams API has documentation on MDN for information on what the platform offers.

For those unfamiliar with Web Streams, try this blog post by Jake Archibald (he is aware the title hasn’t aged well).

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License Apache 2.0