# Functions
# Overview
The Chargebee.js library includes functions that let you carry out activities or fetch information for your customers during the checkout process. For example, you can check the validity of an EU-VAT number before you exempt a customer from taxes.
The following section describes the functions that are currently available in Chargebee.js. Contact Support (opens new window) if you want to see other features supported here.
# Available Functions
# EU-VAT Validation
Chargebee validates VAT Number by sending a validation request to VAT Information Exchange System (VIES (opens new window)), a search engine owned by the European Commission.
Refer here for the implementation details.