Nodejs Child Process: write to stdin from an already initialised process

Question

I am trying to spawn an external process phantomjs using node's child_process and then send information to that process after it was initialized, is that possible?

I have the following code:

var spawn = require('child_process').spawn,
    child = spawn('phantomjs');

child.stdin.setEncoding = 'utf-8';
child.stdout.pipe(process.stdout);

child.stdin.write("console.log('Hello from PhantomJS')");

But the only thing I got on the stdout is the initial prompt for phantomjs console.

phantomjs> 

So it seems the child.stdin.write is not making any effect.

I am not sure I can send additional information to phantomjs ater the initial spawn.

Answer 1

You need to pass also \n symbol to get your command work:

var spawn = require('child_process').spawn,
    child = spawn('phantomjs');

child.stdin.setEncoding('utf-8');
child.stdout.pipe(process.stdout);

child.stdin.write("console.log('Hello from PhantomJS')\n");

child.stdin.end(); /// this call seems necessary, at least with plain node.js executable