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