PhantomJS Shotr - simple script to make webpage shot

shot.js

var page = require('webpage').create(),
    system = require('system'),
    fs = require('fs'),
    uri = document.createElement('a'), // from this https://gist.github.com/2428561
    viewport,
    hash = function(string) {
      var hash = 0,
          char;
    
      if (string.length == 0) return hash;
    
      for (i = 0; i < string.length; i++) {
        char = string.charCodeAt(i);
        hash = ((hash << 5) - hash) + char;
        hash = hash & hash; // Convert to 32bit integer
      }
    
      return hash;
    };
  
if(system.args.length < 2) {
  console.log('Usage: phantomjs ' + system.args[0] + ' url [viewport]');
  phantom.exit();
}
  
page.viewportSize = {
  'width': 1024,
  'height': 728
};

if(system.args[2]) {
  viewport = system.args[2].split('x');
  
  if(!isNaN(viewport[0]) && !isNaN(viewport[1])) {
    page.viewportSize = {
      'width': viewport[0],
      'height': viewport[1]
    };
  }
}

uri.href = system.args[1];

if('file:' == uri.protocol) {
  console.log('Enter valid URL');
  phantom.exit();
}

page.open(system.args[1], function(status) {
  var dir = uri.hostname,
      filename = hash(uri.pathname + uri.search) + '.jpg',
      full_path = dir + fs.separator + filename;
  
  if(!fs.exists(dir) || !fs.isDirectory(dir)) {
    fs.makeDirectory(dir);
  }
  
  page.render(full_path);
  
  console.log(fs.workingDirectory + fs.separator + full_path);
  phantom.exit();
});