Apply business logic using client scripting in model-driven apps using JavaScript

Client-side scripting using JavaScript is one of the ways to apply custom business process logic for displaying data on a form in a model-driven app.

Client scripting shouldn't be your first choice though for applying custom business process logic in model-driven app forms. Business rules provide a way for someone, who doesn't know JavaScript and isn't a developer, to apply business process logic in a form. More information: Create business rules to apply logic. You find the business rule designer within the Data > Tables > [table_name] area on make.powerapps.com. When you view table, look for the Business rules tab.

However, if your business requirement can't be achieved using a business rule, you'll find that client-scripting using the client API object model provides a powerful way to extend the behavior of the application and enable automation in the client.

Forms in model-driven apps help display data to the user. A form in model-driven apps can contain items such as columns, a quick form, or a grid. An event occurs in model-driven apps forms whenever:

• A form loads.
• Data is changed in a column or an item within the form.
• Data is saved in a form.

You can attach your JavaScript code to "react" to these events so that your code gets executed when the event occurs on the form. You attach your JavaScript code (scripts) to these events by using a Script web resource in model-driven apps.

Model-driven apps provide you with a rich set of client APIs to interact with form objects and events to control what and when to display on a form.

Events in forms and grids
Understand the Client API object model
Walkthrough: Write your first client script

Client API reference

Web resources for model-driven apps
Customize commands and the ribbon