All custom fields that come out-of-the-box with Jira have predefined purposes, such as the text field, which allows users to type in some simple text. It will often be useful to have a specialized custom field that does exactly what you need. Unfortunately, this often requires custom development efforts.

However, there is an add-on that provides a custom field type that lets you use Groovy scripts to power its logic.

In this recipe, we will look at how to create a custom field that uses a Groovy script to display the total number of comments on any given issue.