How to check if an arbitrary PID is running using Node.js?

You can call process.kill(pid, 0) and wrap it up in a try/catch.

http://nodejs.org/api/process.html#process_process_kill_pid_signal -

"Will throw an error if target does not exist, and as a special case, a signal of 0 can be used to test for the existence of a process."

Example:

function pidIsRunning(pid) {
  try {
    process.kill(pid, 0);
    return true;
  } catch(e) {
    return false;
  }
}

I needed to check for running pid's in a project as well. I took this answer of using kill -0 <PID> and wrapped it up in a module called is-running https://npmjs.org/package/is-running

npm install is-running