Node.js Piping the same readable stream into multiple (writable) targets

by

You have to create duplicate of the stream by piping it to two streams. You can create a simple stream with a PassThrough stream, it simply passes the input to the output.

const spawn = require('child_process').spawn;
const PassThrough = require('stream').PassThrough;

const a = spawn('echo', ['hi user']);
const b = new PassThrough();
const c = new PassThrough();

a.stdout.pipe(b);
a.stdout.pipe(c);

let count = 0;
b.on('data', function (chunk) {
  count += chunk.length;
});
b.on('end', function () {
  console.log(count);
  c.pipe(process.stdout);
});

Output:

8
hi user

More Related Contents:

  1. How to create streams from string in Node.Js?
  2. Converting a Buffer into a ReadableStream in Node.js
  3. How do I read the contents of a Node.js stream into a string variable?
  4. Why are functions synchronous in Javascript?
  5. await is only valid in async function
  6. How do you get a list of the names of all files present in a directory in Node.js?
  7. nodejs vs node on ubuntu 12.04
  8. Get data from fs.readFile
  9. npm – EPERM: operation not permitted on Windows
  10. Connecting to TCP Socket from browser using javascript
  11. Axios Http client – How to construct Http Post url with form params
  12. Simplest way to wait some asynchronous tasks complete, in Javascript?
  13. node.js shell command execution
  14. Mongoose, Select a specific field with find
  15. Using filesystem in node.js with async / await
  16. Should I refrain from handling Promise rejection asynchronously?
  17. Where is the Socket.IO client-side .js file located?
  18. Get the _id of inserted document in Mongo database in NodeJS
  19. Callback function example
  20. My discord bot code is working but is not responding to my commands [duplicate]
  21. Uncaught (in promise) TypeError: Failed to fetch and Cors error
  22. How to disable Express BodyParser for file uploads (Node.js)
  23. Error [ERR_REQUIRE_ESM]: require() of ES Module not supported [duplicate]
  24. how express forming the img URL
  25. Is there a way to “require” a JS file only once in nodejs?
  26. What does “res.render” do, and what does the html file look like?
  27. How to decipher string in node js which is encrypted in crypto js in javascript
  28. Use of require(lib) versus in Electron apps
  29. Weird behavior with Promise throwing “Unhandled promise rejection” error
  30. Testing asynchronous function with mocha

Leave a Comment