Debug code components

After implementing the code component logic, you can start testing and debugging the code component using the npm start command. This command builds the code component and opens it in the local test harness.


Unsure about entity vs. table? See Developers: Understand terminology in Microsoft Dataverse.

Test harness 1

As the image above shows, the browser window opens with four sections. The code component is rendered in the left pane while the right pane has Context Inputs, Data Inputs, and Outputs sections.

  • Context Inputs provides a way to specify the form factor and test the code component with each form factor (web, tablet, phone). This is helpful when the code component is dependent on a particular form factor capability.

  • Data Inputs is an interactive UI that displays all the properties and their types or type-groups defined in the manifest file. It allows you to key in the mock data for each property.

  • Outputs render the output whenever a component's getOutputs method gets called. 

    Test harness 2


If you want to modify the ControlManifest.Input.xml file or create additional properties, you need to restart the debug process before they appear in the inputs section.

Test code components with mock data

  • For field type components, you can input value and type for every property defined in your ControlManifest.Input.xml as shown here:

    Test harness 2.5

  • For dataset type components, you can load a CSV file with test data. You manually create or export in .csv format directly from your environment. Once a valid CSV file is available, it can be loaded as shown here:

    test harness 3

  • After loading a CSV file, bind each property defined in the ControlManifest.Input.xml to a column in the CSV file. This is done by picking the column for each property as shown here:

    Test harness 4

  • If you don't have any properties defined in the ControlManifest.Input.xml file, then all the columns get automatically loaded into the test harness.

    Test harness 5

Watch mode in test harness

The test harness supports the watch mode, which you can take advantage of for Power Apps component framework projects. To enable watch mode, start the test harness using the command npm start watch. In watch mode, the changes made to any of the following component assets are automatically reflected in the test harness without having to restart it:

  1. index.ts file.
  2. ControlManifest.Input.xml file.
  3. Imported libraries in index.ts.
  4. All the resources listed in the manifest file.

Debug code components using native browsers

You can use the browser's debugging capabilities to observe the component behavior. Each browser provides you with a debugging tool to help you debug your code natively in the browser.

Typically, you can activate debugging in your browser by pressing the F12 key to display the native developer tool used for debugging.

For example, on Microsoft Edge:

  • Press F12 to open the inspector.

  • Select your component.

  • On the top bar, go to Debugger and then search for the component name described in the manifest file in the search bar. For example, type your component name like Hello World component.

    Debug components


It is always a good practice to set breakpoints on the component's lifecycle methods like init and updateView.

You can also interact with the component locally in real time and observe elements in the DOM by setting a breakpoint in the Sources tab as shown here:

Debug component

Fiddler AutoResponder

Use the Fiddler AutoResponder to debug your code components quickly. Install Fiddler and follow the steps to configure AutoResponder.

Power Apps component framework API reference
Power Apps component framework overview


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