Getting ready

To run this recipe, we will need a script that accesses phantom.version. The script in this recipe is available in the downloadable code repository as recipe01.js under chapter02. If we run the provided example script, we must change to the root directory for the book's sample code.

How to do it…

Consider the following script:

console.log('PhantomJS');
console.log('  - major version: ' + phantom.version.major);
console.log('  - minor version: ' + phantom.version.minor);
console.log('  - patch version: ' + phantom.version.patch);
phantom.exit();

Given the preceding script, enter the following at the command line:

phantomjs chapter02/recipe01.js

Our output should look like the following:

PhantomJS
 - major version: 1
 - minor version: 9
 - patch version: 2

How it works…

Our script operates by accessing the version object on the global phantom object and writing its properties (major, minor, and patch) to the console. The build of PhantomJS will have this metadata built in and exposed through phantom.version as read-only information.

Although our example is a trivial one, knowing the specific PhantomJS version at runtime can be helpful for building flexible scripts/libraries. For example, knowing the version at runtime can help us target preferred APIs while still falling back on older or deprecated ones in the event that those APIs are not available.