Screenshot sequence w. node.js and screencapture

gistfile1.js

(function(){
  var sys = require('sys');
  var filestem = process.ARGV.length > 2 ? process.ARGV.length[2] : "screen";

  var spawn = require('child_process').spawn, 
    timer = null, 
    startTime, stopTime;
  
  function outfile(d) {
    d = d || new Date();
    var timestr = (
      d.toLocaleTimeString() +"-"+ 
      d.getUTCMilliseconds()
    ).replace(/\W+/g, '.');
    
    return __dirname + "/" + timestr + "_" + filestem + ".png";
  }
  function start() {
    startTime = new Date();
    stopTime = new Date(startTime.getTime() + 5000);
    tick();
  }
  function tick(){
    if(timer) {
      clearTimeout(timer);
    }
    timer = setTimeout(function(){
      var now = new Date();
      var screencap = spawn("screencapture", ["-T", 0, outfile()]);
      if(now < stopTime) {
        tick();
      } else {
        console.log("done, ", now, stopTime);
      }
    }, 250);
  }
  
  function onCommand(cmd) {
    var parts = cmd.toString().split(/\s+/);
    var verb = parts.shift().toLowerCase().replace(/\s+^/gm, '');
    switch(verb) {
      case "start": 
        console.log("starting...");
        start();
        break;
      case "startin": 
        var delay = Number(parts.shift());
        if(isNaN(delay)) {
          console.log("delay is not a number? " + delay);
        } else {
          console.log("starting in " + delay + " seconds");
          setTimeout(function(){
            start();
          }, delay * 1000);
        }
        break;
      case "stop": 
        console.log("stopping...");
        timer && clearTimeout(timer);
        break;
      default: 
        console.log("huh? what is: " + cmd + " supposed to mean");
    }
  }
 
  console.log("listening for commands (start|stop|startIn)");
  process.stdin.resume(); 
  process.stdin.on('data', onCommand);
})();