Build an Excel task pane add-in

In this article, you'll walk through the process of building an Excel task pane add-in.

Create the add-in

You can create an Office Add-in by using the Yeoman generator for Office Add-ins or Visual Studio. The Yeoman generator creates a Node.js project that can be managed with Visual Studio Code or any other editor, whereas Visual Studio creates a Visual Studio solution. Select the tab for the one you'd like to use and then follow the instructions to create your add-in and test it locally.

Yeoman generator

Prerequisites

Note

If you aren't familiar with Node.js or npm, you should start by setting up your development environment.

• Node.js (the latest LTS version).

• The latest version of Yeoman and the Yeoman generator for Office Add-ins. To install these tools globally, run the following command via the command prompt.

  npm install -g yo generator-office
  

  Note

  Even if you've previously installed the Yeoman generator, we recommend you update your package to the latest version from npm.

Create the add-in project

Run the following command to create an add-in project using the Yeoman generator.

yo office

Note

When you run the yo office command, you may receive prompts about the data collection policies of Yeoman and the Office Add-in CLI tools. Use the information that's provided to respond to the prompts as you see fit.

When prompted, provide the following information to create your add-in project.

• Choose a project type: Office Add-in Task Pane project
• Choose a script type: Javascript
• What do you want to name your add-in? My Office Add-in
• Which Office client application would you like to support? Excel

After you complete the wizard, the generator creates the project and installs supporting Node components.

Tip

You can ignore the next steps guidance that the Yeoman generator provides after the add-in project's been created. The step-by-step instructions within this article provide all of the guidance you'll need to complete this tutorial.

Explore the project

The add-in project that you've created with the Yeoman generator contains sample code for a basic task pane add-in. If you'd like to explore the components of your add-in project, open the project in your code editor and review the files listed below. When you're ready to try out your add-in, proceed to the next section.

• The ./manifest.xml file in the root directory of the project defines the settings and capabilities of the add-in. To learn more about the manifest.xml file, see Office Add-ins XML manifest.
• The ./src/taskpane/taskpane.html file contains the HTML markup for the task pane.
• The ./src/taskpane/taskpane.css file contains the CSS that's applied to content in the task pane.
• The ./src/taskpane/taskpane.js file contains the Office JavaScript API code that facilitates interaction between the task pane and the Office client application.

Try it out

1. Navigate to the root folder of the project.

   cd "My Office Add-in"
   

2. Complete the following steps to start the local web server and sideload your add-in.

   Note

   Office Add-ins should use HTTPS, not HTTP, even while you're developing. If you're prompted to install a certificate after you run one of the following commands, accept the prompt to install the certificate that the Yeoman generator provides. You may also have to run your command prompt or terminal as an administrator for the changes to be made.

   Tip

   If you're testing your add-in on Mac, run the following command before proceeding. When you run this command, the local web server starts.

   npm run dev-server
   

   • To test your add-in in Excel, run the following command in the root directory of your project. This starts the local web server and opens Excel with your add-in loaded.

     npm start
     

   • To test your add-in in Excel on a browser, run the following command in the root directory of your project. When you run this command, the local web server starts. Replace "{url}" with the URL of an Excel document on your OneDrive or a SharePoint library to which you have permissions.

     Note

     If you are developing on a Mac, enclose the {url} in single quotation marks. Do not do this on Windows.

     npm run start:web -- --document {url}
     

     The following are examples.

     • npm run start:web -- --document https://contoso.sharepoint.com/:t:/g/EZGxP7ksiE5DuxvY638G798BpuhwluxCMfF1WZQj3VYhYQ?e=F4QM1R
     • npm run start:web -- --document https://1drv.ms/x/s!jkcH7spkM4EGgcZUgqthk4IK3NOypVw?e=Z6G1qp
     • npm run start:web -- --document https://contoso-my.sharepoint-df.com/:t:/p/user/EQda453DNTpFnl1bFPhOVR0BwlrzetbXvnaRYii2lDr_oQ?e=RSccmNP

     If your add-in doesn't sideload in the document, manually sideload it by following the instructions in Manually sideload add-ins to Office on the web.

3. In Excel, choose the Home tab, and then choose the Show Taskpane button on the ribbon to open the add-in task pane.

   

4. Select any range of cells in the worksheet.

5. At the bottom of the task pane, choose the Run link to set the color of the selected range to yellow.

   

Next steps

Congratulations, you've successfully created an Excel task pane add-in! Next, learn more about the capabilities of an Excel add-in and build a more complex add-in by following along with the Excel add-in tutorial.

Visual Studio

Prerequisites

• Visual Studio 2019 or later with the Office/SharePoint development workload installed.

  Note

  If you've previously installed Visual Studio, use the Visual Studio Installer to ensure that the Office/SharePoint development workload is installed.

• Office connected to a Microsoft 365 subscription (including Office on the web).

  Note

  If you don't already have Office, you can join the Microsoft 365 developer program to get a free, 90-day renewable Microsoft 365 subscription to use during development.

Create the add-in project

1. In Visual Studio, choose Create a new project.

2. Using the search box, enter add-in. Choose Excel Web Add-in, then select Next.

3. Name your project ExcelWebAddIn1 and select Create.

4. In the Create Office Add-in dialog window, choose Add new functionalities to Excel, and then choose Finish to create the project.

5. Visual Studio creates a solution and its two projects appear in Solution Explorer. The Home.html file opens in Visual Studio.

Explore the Visual Studio solution

When you've completed the wizard, Visual Studio creates a solution that contains two projects.

Project	Description
Add-in project	Contains only an XML manifest file, which contains all the settings that describe your add-in. These settings help the Office application determine when your add-in should be activated and where the add-in should appear. Visual Studio generates the contents of this file for you so that you can run the project and use your add-in immediately. You change these settings any time by modifying the XML file.
Web application project	Contains the content pages of your add-in, including all the files and file references that you need to develop Office-aware HTML and JavaScript pages. While you develop your add-in, Visual Studio hosts the web application on your local IIS server. When you're ready to publish the add-in, you'll need to deploy this web application project to a web server.

Update the code

1. Home.html specifies the HTML that will be rendered in the add-in's task pane. In Home.html, replace the <body> element with the following markup and save the file.

   <body class="ms-font-m ms-welcome">
       <div id="content-header">
           <div class="padding">
               <h1>Welcome</h1>
           </div>
       </div>
       <div id="content-main">
           <div class="padding">
               <p>Choose the button below to set the color of the selected range to green.</p>
               <br />
               <h3>Try it out</h3>
               <button class="ms-Button" id="set-color">Set color</button>
           </div>
       </div>
   </body>
   

2. Open the file Home.js in the root of the web application project. This file specifies the script for the add-in. Replace the entire contents with the following code and save the file.

   Note

   The following code uses ES6 JavaScript, which is not compatible with older versions of Office that use the Trident (Internet Explorer 11) browser engine. For information on how to support those platforms in production, see Support older Microsoft webviews and Office versions. Join the Microsoft 365 developer program to get a free, 90-day renewable Microsoft 365 subscription, with the latest Office applications, to use during development.

   'use strict';
   
   (function () {
   
       Office.onReady(function() {
           // Office is ready
           $(document).ready(function () {
               // The document is ready
               $('#set-color').click(setColor);
           });
       });
   
       async function setColor() {
           await Excel.run(async (context) => {
               const range = context.workbook.getSelectedRange();
               range.format.fill.color = 'green';
   
               await context.sync();
           }).catch(function (error) {
               console.log("Error: " + error);
               if (error instanceof OfficeExtension.Error) {
                   console.log("Debug info: " + JSON.stringify(error.debugInfo));
               }
           });
       }
   })();
   

3. Open the file Home.css in the root of the web application project. This file specifies the custom styles for the add-in. Replace the entire contents with the following code and save the file.

   #content-header {
       background: #2a8dd4;
       color: #fff;
       position: absolute;
       top: 0;
       left: 0;
       width: 100%;
       height: 80px;
       overflow: hidden;
   }
   
   #content-main {
       background: #fff;
       position: fixed;
       top: 80px;
       left: 0;
       right: 0;
       bottom: 0;
       overflow: auto;
   }
   
   .padding {
       padding: 15px;
   }
   

Update the manifest

1. In Solution Explorer, go to the ExcelWebAddIn1 add-in project and open the ExcelWebAddIn1Manifest directory. This directory contains your manifest file, ExcelWebAddIn1.xml. The XML manifest file defines the add-in's settings and capabilities. See the preceding section Explore the Visual Studio solution for more information about the two projects created by your Visual Studio solution.

2. The ProviderName element has a placeholder value. Replace it with your name.

3. The DefaultValue attribute of the DisplayName element has a placeholder. Replace it with My Office Add-in.

4. The DefaultValue attribute of the Description element has a placeholder. Replace it with A task pane add-in for Excel.

5. Save the file.

   ...
   <ProviderName>John Doe</ProviderName>
   <DefaultLocale>en-US</DefaultLocale>
   <!-- The display name of your add-in. Used on the store and various places of the Office UI such as the add-ins dialog. -->
   <DisplayName DefaultValue="My Office Add-in" />
   <Description DefaultValue="A task pane add-in for Excel"/>
   ...
   

Try it out

1. Using Visual Studio, test the newly created Excel add-in by pressing F5 or choosing the Start button to launch Excel with the Show Taskpane add-in button displayed on the ribbon. The add-in will be hosted locally on IIS. If you are asked to trust a certificate, do so to allow the add-in to connect to its Office application.

2. In Excel, choose the Home tab, and then choose the Show Taskpane button on the ribbon to open the add-in task pane.

   

3. Select any range of cells in the worksheet.

4. In the task pane, choose the Set color button to set the color of the selected range to green.

   

Note

To see the console.log output, you'll need a separate set of developer tools for a JavaScript console. To learn more about F12 tools and the Microsoft Edge DevTools, visit Debug add-ins using developer tools for Internet Explorer, Debug add-ins using developer tools for Edge Legacy, or Debug add-ins using developer tools in Microsoft Edge (Chromium-based).

Next steps

Congratulations, you've successfully created an Excel task pane add-in! Next, learn more about developing Office Add-ins with Visual Studio.

Code samples

• Excel "Hello world" add-in: Learn how to build a simple Office Add-in with only a manifest, HTML web page, and a logo.

See also

• Office Add-ins platform overview
• Develop Office Add-ins
• Excel JavaScript object model in Office Add-ins
• Excel add-in code samples
• Excel JavaScript API reference
• Using Visual Studio Code to publish