Introduction
To add custom functionality to Dynamics 365 Business Central, you can create a control add-in object, which is a custom control (or visual element) for displaying and modifying data on pages.
A control add-in object is created with the use of AL code and JavaScript. You can use JavaScript to get information from external sources, like REST services, and use it to interact with Business Central by using AL. Therefore, a control add-in object can exchange data on various data types and can respond to user interaction to raise events that run additional AL code.
These objects extend the business solution by surfacing contextual functionality alongside business data. Typical uses of control add-in objects include unique data visualizations, surfacing controls from another service, or displaying (related) content from another data source.
Because it uses JavaScript (and HTML), the control add-in works well in the browser. Furthermore, you can use external JavaScript libraries like jQuery to enhance the possibilities and experiences of a control add-in object.