CODEWITHSUNDEEP
node.jschild-process
André Alçada Padez
André Alçada Padez

Reputation: 11588

send messages from child to parent process

I need to know how can i comunicate from a child process to it's parent. I have tried this:

In my main app:

var spawn = require('child_process').spawn
var cp = spawn('path/to/my/process', params)
cp.on('ready', function(){
  console.log('process is ready')
})

In my child process app:

process.emit('ready')

but the console.log('process is ready') is never executed

Upvotes: 8

Views: 10186

Answers (2)

mvltshn
mvltshn

Reputation: 255

Use process.send() method to send messages from child to parent.

// Parent process
const childProcess = require('child_process');
var process = childProcess.fork('child.js');

process.on('message', function (message) {
    console.log('Message from Child process : ' + message);
});

And in the child 

// child.js 

process.send('HELLO from child')

Upvotes: 3

drowzy
drowzy

Reputation: 667

Sending messages triggers an "message" event. So you could try:

var cp = require('child_process');
var n = cp.fork('path/to/my/process', params);

n.on('message', function(msg) {
  console.log('process is ready');
});

See https://nodejs.org/api/child_process.html#child_process_child_send_message_sendhandle_callback

Upvotes: 1

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