% phantomjs snapshot.js > stdoutfilename

snapshot.js

var page = require('webpage').create();
var url = 'http://localhost:1234/';
page.viewportSize = {
  width: 1024,
  height: 768
};
page.settings.userAgent = 'I am Phantom';
page.open(url, function (a, b, c) {
  setTimeout(function() {
    console.log(page.content);
    phantom.exit();
  }, 2000);

  /*
  // browser JavaScript  call `window.callPhantom` when receive request from PhantomJS
  if (navigator.userAgent.toUpperCase().indexOf('PHANTOM') !== -1) {
    window.callPhantom();
  }
  
  // phantomjs's onCallback
  page.onCallback = function() {
     console.log(page.content);
     phantom.exit();
  };
  */
});

if ('callPhantom' in window) {
  window.callPhantom()
}

also correct?