Build your first Field Customizer extension

Note: The SharePoint Framework Extensions are currently in preview and are subject to change. SharePoint Framework Extensions are not currently supported for use in production environments.

Extensions are client-side components that run inside the context of a SharePoint page. Extensions can be deployed to SharePoint Online and you can use modern JavaScript tools and libraries to build them.

You can also follow these steps by watching the video on the SharePoint PnP YouTube Channel.

Screenshot of the YouTube video player for this tutorial

Create an extension project

Create a new project directory in your favorite location.

md field-extension

Go to the project directory.

cd field-extension

Create a new HelloWorld extension by running the Yeoman SharePoint Generator.

yo @microsoft/sharepoint

When prompted:

  • Accept the default value of field-extension as your solution name and press Enter.
  • Choose Use the current folder and press Enter.
  • Choose N to require extension to be installed on each site explicitly when it's being used.
  • Choose Extension (Preview) as the client-side component type to be created.
  • Choose Field Customizer (Preview) as the extension type to be created.

The next set of prompts will ask for specific information about your extension:

  • Accept the default value of HelloWorld as your extension name and press Enter.
  • Accept the default value of HelloWorld description as your extension description and press Enter.
  • Accept the default No JavaScript Framework as the framework selection and press Enter

Yeoman SharePoint generator prompts to create an extension solution

At this point, Yeoman will install the required dependencies and scaffold the solution files along with the HelloWorld extension. This might take a few minutes.

When the scaffold is complete, you should see the following message indicating a successful scaffold:

SharePoint client-side solution scaffolded successfully

For information about troubleshooting any errors, see Known issues.

Once the solution scaffolding is completed, type the following into the console to start Visual Studio Code.

code .

Notice that because the SharePoint client-side solution is HTML/TypeScript based, you can use any code editor that supports client-side development to build your extension.

Notice how the default solution structure is like the solution structure of client-side web parts. This is the basic SharePoint Framework solution structure with similar configuration options across all solution types.

SharePoint Framework solution opened after initial scaffolding

Open HelloWorldFieldCustomizer.manifest.json at the src\extensions\helloWorld folder.

This file defines your extension type and a unique identifier “id” for your extension. You’ll need this unique identifier later when debugging and deploying your extension to SharePoint.

Application customizer manifest json content

Coding your Field Customizer

Open the HelloWorldFieldCustomizer.ts file in the src\extensions\helloWorld folder.

Notice that the base class for the Field Customizer is imported from the sp-application-base package, which contains SharePoint framework code required by the Field Customizer.

import { Log } from '@microsoft/sp-core-library';
import { override } from '@microsoft/decorators';
import {
} from '@microsoft/sp-listview-extensibility';

The logic for your Field Customizer is contained in the OnInit(), onRenderCell(), and onDisposeCell() methods.

  • onInit(): this is where you should perform any setup needed for your extension. This event occurs after this.context and are assigned, but before the page DOM is ready. As with web parts, onInit() returns a promise that you can use to perform asynchronous operations; onRenderCell() will not be called until your promise has resolved. If you don’t need that, simply return Promise.resolve<void>();.
  • onRenderCell(): This event occurs when each cell is rendered. It provides an event.domElement HTML element where your code can write its content.
  • onDisposeCell(): This event occurs immediately before the event.cellDiv is deleted. It can be used to free any resources that were allocated during field rendering. For example, if onRenderCell() mounted a React element, onDisposeCell() must be used to free it, otherwise a resource leak would occur. 

Below are the contents of onRenderCell() and onDisposeCell() in the default solution:

  public onRenderCell(event: IFieldCustomizerCellEventParameters): void {
    // Use this method to perform your custom cell rendering.
    const text: string = `['${event.fieldValue}']`;

    event.domElement.innerText = text;


  public onDisposeCell(event: IFieldCustomizerCellEventParameters): void {
    // This method should be used to free any resources that were allocated during rendering.
    // For example, if your onRenderCell() called ReactDOM.render(), then you should
    // call ReactDOM.unmountComponentAtNode() here.

Debugging your Field Customizer using gulp serve and query string parameters

SharePoint Framework extensions cannot currently be tested using the local workbench, so you'll need to test and develop them directly against a live SharePoint Online site. You do not however need to deploy your customization to the app catalog to do this, which keeps the debugging experience simple and efficient.

First, compile your code and host the compiled files from the local machine by running this command:

gulp serve --nobrowser

Notice that we used the --nobrowser option, since there's no value in launching the local workbench since you currently cannot debug extensions locally.

Once it compiles the code without errors, it will serve the resulting manifest from https://localhost:4321.

gulp serve

To test your extension, navigate to a site in your SharePoint Online tenant.

Move to the Site Contents page.

Click New from the toolbar and choose List:

Creating a new list

Create a new list named Orders and click Create:

Creating a new list with name of Orders

Click the plus sign and choose Number to create a new Number field for the list:

Creating a new Number field

Set name of the field to Percent and click Save:

Creating a new field called Percent

Add a few items with different numbers in the percent field. We'll modify the rendering later in this tutorial, so the different numbers will be presented differently based on your custom implementation.

Creating items in the newly created list with different values in the Percent field

Since our Field Customizer is still hosted in localhost and is running, we can use specific debug query parameters to execute the code in the newly created list.

Append the following query string parameters to the URL. Notice that you will need to update the id to match your own extension identifier available from the HelloWorldFieldCustomizer.manifest.json file:


More detail about the URL query parameters:

  • loadSPFX=true: ensures that the SharePoint Framework is loaded on the page. For performance reasons, the framework is not normally loaded unless at least one extension is registered. Since no components are registered yet, we must explicitly load the framework.
  • debugManifestsFile: specifies that we want to load SPFx components that are being locally served. Normally the loader only looks for components in the App Catalog (for your deployed solution) and the SharePoint manifest server (for the system libraries).
  • fieldCustomizers: Indicates which fields in your list should have their rendering controlled by the Field Customizer. The ID parameter specifies the GUID of the extension that should be used to control the rendering of the field. The properties parameter is an optional text string containing a JSON object that will be deserialized into for your extension.
    • Key: use the internal name of the field as the key
    • Id: the guid of the field customizer extension associated with this field
    • Properties: property values defined in the extension. In this example, ‘sampleText’ is a property defined by the extension

The full URL should look similar to the following, depending on your tenant URL and the location of the newly created list:{"Percent":{"id":"7e7a4262-d02b-49bf-bfcb-e6ef1716aaef","properties":{"sampleText":"Hello!"}}}

Accept the loading of Debug Manifests, by clicking Load debug scripts when prompted:

Accept loading debug scripts

Notice how the Percent values are now presented with additional [ ] characters:

Accept loading debug scripts

Enhancing the Field Customizer rendering

Now that we have successfully tested the out of the box starting point of the Field Customizer, let's modify the logic slightly to have a more polished rendering of the field value.

Open the HelloWorld.module.scss file in the src\extensions\helloWorld folder and update the styling definition as follows.

.HelloWorld {
  .cell {
    display: 'inline-block';
  .full {
    background-color: '#e5e5e5';
    width: '100px';

Open the HelloWorldFieldCustomizer.ts file in the src\extensions\helloWorld folder and update the onRednerCell method as follows.

  public onRenderCell(event: IFieldCustomizerCellEventParameters): void {

    event.domElement.innerHTML = `
                <div class='${styles.full}'>
                  <div style='width: ${event.fieldValue}px; background:#0094ff; color:#c0c0c0'>
                    &nbsp; ${event.fieldValue}

Switch back to your console window and ensure that you do not have any exceptions. If you do not have the solution running in localhost, execute the following command:

gulp serve --nobrowser

Move back to your previously created list and use the same query parameter as used previously with the Field being 'Percent' and the Id being updated to your extension identifier available from the HelloWorldFieldCustomizer.manifest.json file.

Accept the loading of Debug Manifests, by clicking Load debug scripts when prompted.

Accept loading debug scripts

Notice how we have changed the field rendering style completely. The field value is indicated using a graphical representation of the value.

Graphical Representation of Percent

Add the field definition to the solution package for deployment

Now that we have tested our solution properly in debug mode, we can package this to be deployed automatically as part of the solution package deployed to the sites. There are few things to take care of here.

  1. Install the solution package to the site where it should be installed, so that the extension manifest is being white listed for execution
  2. Associate the Field Customizer to an existing field in the site. This can be performed programmatically (CSOM/REST) or by using the feature framework inside of the SharePoint Framework solution package. You'll need to associate the following properties in the SPField object at the site or list level.
    • ClientSiteComponentId: This is the identifier (GUID) of the Field Customizer, which has been installed in the app catalog.
    • ClientSideComponentProperties: This is an optional parameter, which can be used to provide properties for the Field Customizer instance.

Notice, you can control the requirement to add a solution containing your extension to the site by using skipFeatureDeployment setting in package-solution.json. Event though you would not require solution to be installed on the site, you'd need to associate ClientSideComponentId to specific objects for the extension to be visible.

In the following steps, we'll create a new field definition, which will then be automatically deployed with the needed configurations when the solution package is installed on a site.

Return to your solution in Visual Studio Code (or to your preferred editor).

We'll first need to create an assets folder where we will place all feature framework assets used to provision SharePoint structures when the package is installed.

  • Create a folder named sharepoint in the root of the solution
  • Create a folder named assets as a sub folder of the just created sharepoint folder

Your solution structure should look similar to the following picture:

assets folder in solution structure

Add an elements.xml file for SharePoint definitions

Create a new file inside the sharepoint\assets folder named elements.xml

Copy the following xml structure into elements.xml. Be sure to update the ClientSideComponentId property to the unique Id of your Field Customizer available in the HelloWorldFieldCustomizer.manifest.json file in the** src\extensions\helloWorld** folder.

<?xml version="1.0" encoding="utf-8"?>
<Elements xmlns="">

    <Field ID="{060E50AC-E9C1-3D3C-B1F9-DE0BCAC200F6}"
            Group="SPFx Columns"


Ensure that definitions are taken into account within the build pipeline

Open package-solution.json from the config folder. The package-solution.json file defines the package metadata as shown in the following code:

  "solution": {
    "name": "field-extension-client-side-solution",
    "id": "11cd343e-1ce6-462c-8acb-929804d0c3b2",
    "version": "",
    "skipFeatureDeployment": false
  "paths": {
    "zippedPackage": "solution/field-extension.sppkg"

To ensure that our newly added elements.xml file is taken into account while solution is being packaged, we'll need to include a Feature Framework feature definition for the solution package. Let's include a JSON definition for the needed feature inside of the solution structure as demonstrated below.

  "solution": {
    "name": "field-extension-client-side-solution",
    "id": "11cd343e-1ce6-462c-8acb-929804d0c3b2",
    "version": "",
    "skipFeatureDeployment": false,
    "features": [{
      "title": "Field Extension - Deployment of custom field.",
      "description": "Deploys a custom field with ClientSideComponentId association",
      "id": "123fe847-ced2-3036-b564-8dad5c6c6e83",
      "version": "",
      "assets": {        
        "elementManifests": [
  "paths": {
    "zippedPackage": "solution/field-extension.sppkg"

Deploy the field to SharePoint Online and host JavaScript from local host

Now you are ready to deploy the solution to a SharePoint site and to get the field association automatically included in a field.

In the console window, enter the following command to package your client-side solution that contains the extension, so that we get the basic structure ready for packaging:

gulp bundle

Next, execute the following command so that the solution package is created:

gulp package-solution

The command will create the package in the sharepoint/solution folder:


Next you need to deploy the package that was generated to the App Catalog.

Go to your tenant's App Catalog and open the Apps for SharePoint library.

Upload or drag and drop the field-extension.sppkg located in the sharepoint/solution folder to the App Catalog. SharePoint will display a dialog and ask you to trust the client-side solution.

Notice that we did not update the URLs for hosting the solution for this deployment, so the URL is still pointing to https://localhost:4321. Click the Deploy button.

Deploy Dialog

Go to the site where you want to test SharePoint asset provisioning. This could be any site collection in the tenant where you deployed this solution package.

Choose the gears icon on the top navigation bar on the right and choose Add an app to go to your Apps page.

In the Search box, enter 'field' and press Enter to filter your apps.

installing field customizer to site

Choose the field-extension-client-side-solution app to install the solution on the site. Once the installation is completed, refresh the page by pressing F5.

When the solution has been installed, Click New from the toolbar in Site Contents page and choose List:

Creating a new list

Create a list named Invoices:

When the new list has been created, move back to the Site Contents page and choose Settings from the context menu of the just created list:

List settings for the new list

Choose Add from existing site columns under the Columns section:

Choose the Percentage field which was provisioned from the solution package, under the SPFx Columns group:

List settings for the new list

Click OK.

Move back to your console and ensure that the solution is running. If it's not running, execute the following command in the solution folder:

gulp serve --nobrowser

Navigate to the newly created Invoices list and add a few new items to the list with different values in the Percentage column to see how the field is being rendered without the Debug query parameters.

Field Rendering without Debug Query Parameters

In this case, we continued to host the JavaScript from the localhost, but you could just as well relocate the assets to any CDN and update the URL to enable the loading of the JavaScript assets outside of the localhost as well.

The process for publishing your app is identical among the different extension types. You can follow the following publishing steps to update the assets to be hosted from a CDN.