To run this recipe, we will need a script that loads a web page with hover effects or similar features that are sensitive to the mousemove event; our script needs to expect to interact with these mousemove events.

The script in this recipe is available in the downloadable code repository as recipe10.js under chapter03. If we run the provided example script, we must change to the root directory for the book's sample code.

Lastly, the script in this recipe runs against the demo site that is included with the cookbook's sample code repository. To run that demo site, we must have Node.js installed. In a separate terminal, change to the phantomjs-sandbox directory (in the sample code's directory), and start the app with the following command:

node app.js

Consider the following script:

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

webpage.viewportSize...