nodejs: do not wait spawned process

Question

I am using child_process.spawn for running some app and I want to execute some actions after this app was started. But spawn blocks main process

const spawnAsync = Promise.promisify(require('child_process').spawn);
console.log('BEFORE');   
await spawnAsync('../node_modules/.bin/some-app', ['-p', '3333'], {
    detached: true
});
console.log('AFTER');

In my console, I see BEFORE and AFTER would be logged only after killing process on 3333 port. I don't want to wait spawned process, I want to do some actions after spawnSync calling.

Answer 1

Looking at spawn documentation you should use it that way

const childProcess = require('child_process');

const newProcessDescriptor = childProcess.spawn(
    '../node_modules/.bin/some-app', 
    ['-p', '3333'], 
    { detached: true }
);
      
newProcessDescriptor.on('error', (error) => {
    console.log(`child process creating error with error ${error}`);
});

newProcessDescriptor.on('close', (code) => {
    console.log(`child process exited with code ${code}`);
});