npm install connect-assets-hbs-helpers
Simply require 'connect-assets-hbs-helpers' in your express server, and setup connect-assets (check link for instructions)
In your handlebars templates you can now use these helpers:
{{{css 'horse' 'screen and (max-device-width: 480px)'}}}
{{{js 'monkey'}}}
{{{img 'screenshots/panda'}}}