How to exclude for mobile devices

Problem/Motivation

In the documentation on the source website where this code comes from (http://www.schillmania.com/projects/snowstorm/#customizing) is says you can customise the snow effect to exclude it from showing on mobile devices. I've tried to do this by adding the following code to the snowstorm.js file:

this.excludeMobile = true;

but it doesn't work. Any suggestions?