trying to run perfmap on phantomjs

perfcap.js

var page = require('webpage').create();

page.onConsoleMessage = function(msg) {
  console.log('INFO: ' + msg);
};

page.open('http://www.example.com', function() {

    page.evaluate(function() {
	var el=document.createElement('script');
	el.src='https://zeman.github.io/perfmap/perfmap.js';
	document.body.appendChild(el);
    });
    
    page.render('screenshot.png');
    phantom.exit()
});