PhantomJS

Quick Start

This instruction assumes that PhantomJS is installed and its executable is placed somewhere in the PATH.

The code shown here is also available in ​​various examples​​​ included with PhantomJS. You are also recommended to explore the use of PhantomJS for ​​page automation​​​, ​​network monitoring​​​, ​​screen capture​​​, and ​​headless testing​​.

Hello, World!

Create a new text file that contains the following two lines:

console.log('Hello, world!');
phantom.exit();

Save it as ​​hello.js​​ and then run it from the command line, not the REPL.

REPL is a simple, interactive computer programming environment. Read about REPL in the docs ​​Here​​. Again, REPL is the executable phantomjs.exe not the command line.

From the command prompt type:

phantomjs hello.js

The output is:

Hello, world!

In the first line, ​​console.log​​​ will print the passed string to the terminal. In the second line, ​​phantom.exit​​ terminates the execution.

It is very important to call ​​phantom.exit​​ at some point in the script, otherwise PhantomJS will not be terminated at all.

Page Loading

A web page can be loaded, analyzed, and rendered by creating a web page object.

The following script demonstrates the simplest use of page object. It loads example.com and then saves it as an image, ​​example.png​​ in the same directory the script was run in.

var page = require('webpage').create();
page.open('http://example.com', function(status) {
  console.log("Status: " + status);
  if(status === "success") {
    page.render('example.png');
  }
  phantom.exit();
});

Because of its rendering features, PhantomJS can be used to ​​capture web pages​​, essentially taking a screenshot of the contents.

The following ​​loadspeed.js​​ script loads a specified URL (do not forget the http protocol) and measures the time it takes to load it.

var page = require('webpage').create(),
  system = require('system'),
  t, address;

if (system.args.length === 1) {
  console.log('Usage: loadspeed.js <some URL>');
  phantom.exit();
}

t = Date.now();
address = system.args[1];
page.open(address, function(status) {
  if (status !== 'success') {
    console.log('FAIL to load the address');
  } else {
    t = Date.now() - t;
    console.log('Loading ' + system.args[1]);
    console.log('Loading time ' + t + ' msec');
  }
  phantom.exit();
});

Run the script with the command:

phantomjs loadspeed.js http://www.google.com

It outputs something like:

Loading http://www.google.com Loading time 719 msec

Code Evaluation

To evaluate JavaScript code in the context of the web page, use ​​evaluate()​​​ function. The execution is “sandboxed”, there is no way for the code to access any JavaScript objects and variables outside its own page context. An object can be returned from ​​evaluate()​​, however it is limited to simple objects and can’t contain functions or closures.

Here is an example to show the title of a web page:

var page = require('webpage').create();
page.open(url, function(status) {
  var title = page.evaluate(function() {
    return document.title;
  });
  console.log('Page title is ' + title);
  phantom.exit();
});

Any console message from a web page, including from the code inside ​​evaluate()​​​, will not be displayed by default. To override this behavior, use the ​​onConsoleMessage​​ callback. The previous example can be rewritten to:

var page = require('webpage').create();
page.onConsoleMessage = function(msg) {
  console.log('Page title is ' + msg);
};
page.open(url, function(status) {
  page.evaluate(function() {
    console.log(document.title);
  });
  phantom.exit();
});

Since the script is executed as if it is running on a web browser, standard DOM scripting and CSS selectors work just fine. It makes PhantomJS suitable to carry out various ​​page automation tasks​​.

Network Requests and Responses

When a page requests a resource from a remote server, both the request and the response can be tracked via ​​onResourceRequested​​​ and ​​onResourceReceived​​​ callback. This is demonstrated in the example ​​netlog.js​​:

var page = require('webpage').create();
page.onResourceRequested = function(request) {
  console.log('Request ' + JSON.stringify(request, undefined, 4));
};
page.onResourceReceived = function(response) {
  console.log('Receive ' + JSON.stringify(response, undefined, 4));
};
page.open(url);

​​http://phantomjs.org/quick-start.html​​