If you are using PushAssist WordPress plugin, you don't have to add any JS code within your site since the plugin installs it automatically.
If you run or own a WordPress based site you can simply install the PushAssist WordPress plugin from WordPress.org which will handle everything for you. It works well for all WordPress installations i.e. WooCommerce, Cart66, Wp-eCommerce, BBPress or any paid or free plugins available for WordPress.
Primarily, you should have
hook placed in your footer file for the plugin to install the JS script to work.