Maintain access to console while running Node.js program

Question

Can I send commands to Node.js process running a .js script? Currently I just run node and paste my code into console. It's not very convenient.

Answer 1

You can start a repl server (that has access to the script's scope) like this:

var repl = require('repl'),
    net = require('net');

var REPL_PORT = 2323;

var replServer = net.createServer(function(sock) {
  repl.start({
    prompt: 'myrepl> ',
    input: sock,
    output: sock,
    eval: function(cmd, context, filename, callback) {
      var ret, err;
      try {
        ret = eval(cmd);
      } catch (e) {
        err = e;
      }
      if (err)
        callback(err);
      else
        callback(null, ret);
    }
  }).on('exit', function() {
    sock.end();
  });
});
replServer.on('error', function(err) {
  console.log('REPL error: ' + err);
});
replServer.on('close', function(had_err) {
  console.log('REPL shut down ' + (had_err ? 'due to error' : 'gracefully'));
});
replServer.on('listening', function() {
  console.log('REPL listening on port ' + REPL_PORT);
});
replServer.listen(REPL_PORT, '127.0.0.1');

Then just telnet to localhost at port 2323 and you'll get a repl prompt that you can type stuff into and poke at variables and such that are defined in your script.