Phantom-Test.js

var page = require('webpage').create(),
    url = 'http://localhost:1134/test_client.html';

//Visit the specified url
page.open(url, function (status) {
	check(step1);
});

//Fill in the command and click 'Go!'
function step1(){
	page.evaluate(function() {
		document.getElementsByName('command')[0].value = 'whoami';				   
		document.getElementById('execute').click();
	});
	check(step2);
}

//Log the output
function step2(){
	page.evaluate(function() {	
		console.log(document.getElementById('output').innerHTML);
	});
	phantom.exit();
}

//Check and wait for the 'Go!' button to be enabled
function check(step){	
	state = page.evaluate(function() {		   
		return document.getElementById('execute').getAttribute('aria-disabled') == "false" && document.getElementById('output').innerHTML !='';
	});

  if(!state)
		setTimeout(function(){
			check(step);
		},50);
  else
		step();
};