Catalog client script is a JavaScript code which executes when user orders any catalog item. In this video practical demonstration of implementing use case is given. That how the developer can customize the catalog item and can write the various type of catalog client script in servicenow
There are three types of catalog client script:
1. onload
2. onChange
3. onSubmit
Every catalog item has its own client script. We can also write catalog client script for the variable set used in a catalog item.