@withremyinc/stream

Composable helpers for the Web Streams API, plus incremental JSON and XML parsers for text and AI pipelines.

• ESM-only
• Node 18+
• Web Streams-native APIs
• Small functional helpers for ReadableStream / TransformStream
• Tolerant streaming parsers for JSONC-style JSON and XML fragments

Installation

npm install @withremyinc/stream

pnpm add @withremyinc/stream

yarn add @withremyinc/stream

Quick start

import { arrayStream, collect, filter, map } from "@withremyinc/stream";

const output = await collect(
  arrayStream([1, 2, 3, 4])
    .pipeThrough(map((value) => value * 2))
    .pipeThrough(filter((value) => value > 4)),
);

console.log(output); // [6, 8]

What is included?

Stream helpers

Sources / composition

• arrayStream()
• merge()
• mergeKeyed()
• concat()
• pipeThrough()
• tee()

pipeThrough() composes multiple TransformStreams into a single transform when you want to pass around a whole pipeline.

Collectors

• collect()
• collectFirst()
• collectLast()
• collectToString()

Transforms

• map()
• filter()
• filterMap()
• flatMap()
• scan()
• reduce()
• take()
• takeLast()
• drop()
• toArray()
• toString()
• forEach()
• some()
• every()
• find()
• extractDelimiter()

Streaming JSON

parseJSON() tokenizes and parses JSON incrementally and emits visit events. jsonToJSObject() folds those events back into a plain JavaScript value.

It is intentionally tolerant of JSONC-style input such as comments and trailing commas.

import {
  arrayStream,
  collect,
  jsonToJSObject,
  parseJSON,
  takeLast,
} from "@withremyinc/stream";

const [value] = await collect(
  arrayStream(['{ "name": "Remy", /* comment */ }'])
    .pipeThrough(parseJSON())
    .pipeThrough(jsonToJSObject())
    .pipeThrough(takeLast(1)),
);

console.log(value); // { name: "Remy" }

Streaming XML

parseXML() incrementally parses XML documents or fragments and emits events such as:

• onDocumentBegin
• onElementBegin
• onText
• onElementEnd
• onError

It is non-validating and recovery-oriented, which makes it useful for LLM output and other imperfect text streams.

import { arrayStream, collect, parseXML } from "@withremyinc/stream";

const events = await collect(
  arrayStream(["<root><item>Hello</item></root>"]).pipeThrough(parseXML()),
);

console.log(events);

If you only want specific top-level XML islands from mixed text, use extractXML():

import { arrayStream, collect, extractXML } from "@withremyinc/stream";

const events = await collect(
  arrayStream([
    'before <answer confidence="0.9">hello</answer> after',
  ]).pipeThrough(extractXML({ allowTags: ["answer"] })),
);

Delimited block extraction

extractDelimiter() streams the body of the first matching fenced block and drops the fence lines. This is handy for extracting Markdown code fences before passing the contents into parseJSON() or parseXML().

import {
  arrayStream,
  collectToString,
  extractDelimiter,
} from "@withremyinc/stream";

const body = await collectToString(
  arrayStream([
    "ignore this\n```json\n",
    '{"ok": true}\n',
    "```\ntrailing text",
  ]).pipeThrough(extractDelimiter({ allowLanguages: ["json"] })),
);

console.log(body); // {"ok": true}\n

Development

Published output targets Node 18+, but local builds currently require Node 20.19+ because tsdown does. .nvmrc and .node-version are included for that toolchain.

pnpm install
pnpm test
pnpm typecheck
pnpm build

Extra scripts:

• pnpm bench:geojson
• pnpm bench:xml

Changelog

See CHANGELOG.md.

Releasing

For the full checklist, see RELEASING.md.

Quick version:

1. Bump the package version with pnpm version patch (or minor / major).
2. Push the commit and matching tag with git push --follow-tags.
3. GitHub Actions publishes that tag to npm.

The publish workflow expects an NPM_TOKEN repository secret and uses npm provenance.

Release notes / packaging

This package publishes the built dist/ output plus:

• README.md
• CHANGELOG.md
• LICENSE.md
• NOTICES.md

License

MIT.

Copyright © 2026 Remy, Inc.

See LICENSE.md for the project license and NOTICES.md for bundled third-party notices.