Here’s a detailed article that explains how to define the TypeScript version you want to use in SharePoint Framework (SPFx)

How to Define the TypeScript Version in SharePoint Framework (SPFx)

SharePoint Framework (SPFx) is a robust development model that leverages web standards to allow developers to extend SharePoint and create custom solutions. By default, SPFx projects are set to use a specific TypeScript version, but there are instances where you might want to upgrade or downgrade the TypeScript version based on your needs.

In this guide, we’ll explore how you can define the TypeScript version you want to use in your SPFx projects, the implications of changing the TypeScript version, and the best practices for managing this process effectively.

Why Change the TypeScript Version?

TypeScript evolves rapidly, and newer versions bring improvements in terms of features, performance, and type-checking capabilities. However, SPFx doesn’t always upgrade to the latest TypeScript version immediately. This can leave developers in a situation where they might want to leverage features of a newer TypeScript version or need to use a specific version that matches their environment or team standards.

Step-by-Step Guide to Defining a TypeScript Version in SPFx

1. Verify the Current TypeScript Version in Your SPFx Project
   By default, SPFx projects come with a specific version of TypeScript defined in the @microsoft/gulp-core-build-typescript package. To check the version of TypeScript that is currently being used, follow these steps:

• Open the package.json file of your SPFx project.
• Search for the @microsoft/gulp-core-build-typescript package in the devDependencies.
• This package locks the TypeScript version used by SPFx.

1. Install a Specific TypeScript Version
   To install a specific TypeScript version, you need to install it locally within your SPFx project. This ensures that your SPFx build process uses the TypeScript version you specify instead of the one defined by the framework. Run the following command to install a specific TypeScript version (e.g., TypeScript 4.2.3):

   npm install typescript@4.2.3 --save-dev

This command will install TypeScript as a development dependency and ensure that the desired version is used in your SPFx project.

3. Update the TypeScript Path in tsconfig.json
   After installing the desired TypeScript version, update the tsconfig.json file to use this version. The tsconfig.json file contains configuration options for your TypeScript project, including which TypeScript version to use. Modify or add the following configuration under the compilerOptions section of your tsconfig.json:

   {
     "compilerOptions": {
       "typescript": "./node_modules/typescript"
     }
   }

This tells SPFx to use the locally installed TypeScript version from the node_modules folder instead of the default one.

4. Update the Build Process
   You may need to update the SPFx build process to ensure it uses your custom TypeScript version. You can do this by modifying the gulpfile.js in your SPFx project. Here’s how to ensure the custom TypeScript version is used:

• Locate your gulpfile.js.
• Import the typescript package from node_modules if not already present: const typescript = require('typescript');
• Override the TypeScript version used in the build configuration by adding the following code: build.configureWebpack.mergeConfig({ additionalConfiguration: (generatedConfiguration) => { generatedConfiguration.resolve.alias = { 'typescript': require.resolve('typescript') }; return generatedConfiguration; } }); This ensures the correct TypeScript version is used in the build process.

4. Verify the Changes
   After making these changes, run a build to ensure everything is working correctly. Use the following command to compile your project and check for any errors:

   gulp build

If there are no errors, your SPFx project is now using the custom TypeScript version you’ve installed. If you encounter issues, double-check the version compatibility between SPFx and the TypeScript version you are using.

Things to Keep in Mind

• SPFx Compatibility: Always verify whether the TypeScript version you’re upgrading to is compatible with your version of SPFx. Microsoft frequently updates the supported TypeScript versions with new SPFx releases.
• Backward Compatibility: If you’re working in a team, ensure that all developers use the same TypeScript version to avoid inconsistencies. Consider using a version-locking tool like npm shrinkwrap or yarn.lock to manage this.
• New Features: If you’re using newer TypeScript versions, you might have access to features not available in the default SPFx TypeScript version. However, be cautious and ensure that these features don’t break existing SPFx functionalities.

Summary of Commands and Files

By following the steps in this guide, you’ll be able to customize the TypeScript version used in your SPFx projects, allowing you to leverage newer features and maintain compatibility with your development environment.

This approach gives you flexibility while ensuring that your project adheres to your development standards.