cam.js

var gpio = require("gpio");
var RaspiCam = require("raspicam");
var moment = require('moment');
var camera = new RaspiCam({
	mode: 'photo',
	output: timestring+'.jpg'
});

camera.on("started", function(){ 
   console.log('started');
});
 
//listen for the "read" event triggered when each new photo/video is saved
camera.on("read", function(err, filename){ 
   console.log('err:' + err);
   console.log('filename:' + filename);
});
 
//listen for the process to exit when the timeout has been reached
camera.on("exited", function(){
   console.log('exited');
});

var shutter = gpio.export(4, {
   direction: "in",
   interal: 100000,
   ready: function() {
     console.log('button in mode ready');
   }
});

shutter.on("change", function(val) {
   // value will report either 1 or 0 (number) when the value changes
   //console.log(val);
   switch(val)
   {
     case 0:
       console.log('press');
       break;
     case 1:
       console.log('release');
       var timestring = moment().format('YYYY-MM-DD HH.MM.SS');
 
      camera = new RaspiCam({
      	mode: 'photo',
      	output: timestring+'.jpg'
      });
       
      //to take a snapshot, start a timelapse or video recording
      camera.start( );
       
       break;
   }
});