Quick Start with PhantomJS

PhantomJS is a command-line tool. Make sure that you are familiar with the use of the command prompt or PowerShell (on Windows) or a terminal (on macOS and Linux).

This instruction assumes that PhantomJS is installed and placed somewhere in the PATH (e.g. see this tutorial for Windows users).

Hello, World!

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

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

phantomjs hello.js

Hello, world!

Page Loading

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

Further Study

The code shown above 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.