@techmely/utils/mergeStreams.mjs

Collection of helpful JavaScript / TypeScript utils

import { invariant } from './chunk-JBXZG2HJ.mjs';
import { isArray } from './chunk-UGDKU24C.mjs';
import './chunk-NYLAFCGV.mjs';
import { PassThrough } from 'node:stream';

function mergeStreams(streams) {
  invariant(isArray(streams), "Expect input an array streams");
  const passThroughStream = new PassThrough({ objectMode: true });
  if (streams.length === 0) {
    passThroughStream.end();
    return passThroughStream;
  }
  let streamsCount = streams.length;
  for (const stream of streams) {
    invariant(!(typeof stream?.pipe === "function"), "Expect a stream, got ");
    stream.pipe(passThroughStream, { end: false });
    stream.on("end", () => {
      streamsCount--;
      if (streamsCount === 0) {
        passThroughStream.end();
      }
    });
    stream.on("error", (error) => {
      passThroughStream.emit("error", error);
    });
  }
  return passThroughStream;
}

export { mergeStreams };