Example: running a process and piping output back to web client

spawn-express.js

import { spawn } from 'child_process';

// app is an express server
app.get('/some/url/:someOption' function(req, res, next) {
    let { someOption  } = req.params;

    let commandProcess = spawn('node', ['someScript.js', someOption]);
    commandProcess.stdout.setEncoding('utf8');

    commandProcess.stderr.pipe(process.stderr);

    commandProcess.stdin.write("something on std in");
    commandProcess.stdin.end();

    commandProcess.stdout.pipe(res);
});