10 tsconfig Best Practices

tsconfig.json is the configuration file for TypeScript projects. It is used to define the compiler options, the files and directories to be included in the compilation, and other project-wide settings.

In this article, we will discuss 10 best practices for using tsconfig.json. These best practices will help you ensure that your TypeScript projects are configured correctly and that you are taking full advantage of the features available in TypeScript.

1. Use the compilerOptions object to define your project’s settings

The compilerOptions object is a powerful tool for configuring the TypeScript compiler. It allows you to specify settings such as target language version, module resolution strategy, and more. This makes it easy to ensure that your project’s code is compiled correctly and consistently across different environments.

Using the compilerOptions object also helps keep your tsconfig file organized and readable. By defining all of your project’s settings in one place, you can easily see what options are being used and make changes if needed. Additionally, since the compilerOptions object is an object literal, you can use comments to explain each setting and provide additional context.

2. Use strict type checking mode for better code quality

Strict type checking mode enables the TypeScript compiler to perform additional checks on types, which can help catch errors early in the development process. This is especially useful when working with complex codebases or large teams of developers, as it helps ensure that all code is consistent and follows best practices.

To enable strict type checking mode, you need to set the “strict” flag to true in your tsconfig file. This will tell the compiler to perform more rigorous type checking and enforce stricter rules for type safety. Additionally, you may also want to set the “noImplicitAny” flag to true, which will prevent the compiler from automatically inferring any types.

3. Set target to ES2020 or higher to ensure compatibility with modern browsers

The target option in tsconfig.json specifies the JavaScript version to which TypeScript should compile your code. By setting it to ES2020 or higher, you can take advantage of all the latest features and syntax available in modern browsers. This helps ensure that your code will run correctly on any browser that supports those versions of ECMAScript.

To set the target to ES2020 or higher, simply add “target”: “ES2020” (or whichever version you want) to your tsconfig.json file. You can also use the –target flag when running tsc from the command line.

4. Use skipLibCheck to speed up compilation time

skipLibCheck is a boolean flag that can be set to true in the tsconfig.json file, and it tells the TypeScript compiler to skip type checking of declaration files (e.g. .d.ts files). This speeds up compilation time significantly because these files are usually large and complex, and they don’t need to be checked for correctness since they’re already pre-compiled.

The downside of using skipLibCheck is that it may lead to false positives or false negatives when compiling code. For example, if you have an incorrect type annotation in a declaration file, the compiler won’t catch it if skipLibCheck is enabled. However, this risk can be mitigated by making sure all declaration files are correct before enabling skipLibCheck.

5. Use jsxFactory and reactNamespace to customize JSX output

Using jsxFactory allows developers to specify the function that is used when compiling JSX expressions. This can be useful for customizing the output of a React component, as it allows developers to use their own naming conventions and other preferences. For example, if you want to prefix all your components with “MyCompany”, you can set up a jsxFactory in tsconfig that will automatically add this prefix to each component name.

The reactNamespace option also helps customize JSX output by allowing developers to specify the namespace that should be used when compiling JSX expressions. This is especially helpful when working with multiple libraries or frameworks that have different namespaces. By setting up a reactNamespace in tsconfig, developers can ensure that all JSX expressions are compiled using the correct namespace.

6. Use paths and baseUrl to simplify import statements

Using paths and baseUrl allows you to create aliases for your import statements, which makes them much easier to read and understand. For example, instead of writing out the full path to a file every time you need to import it, you can simply use an alias like “@/components/Button”. This also helps keep your code DRY (Don’t Repeat Yourself) since you don’t have to write out the same long path multiple times.

To set up paths and baseUrl in tsconfig, you first need to define the baseUrl property. This is the root directory from which all relative imports will be resolved. Then, you can add entries to the paths object that map aliases to specific directories or files. Once this is done, you can use these aliases in your import statements instead of the full path.

7. Set noEmitOnError to true to prevent emitting invalid JavaScript

When noEmitOnError is set to true, the TypeScript compiler will not emit JavaScript if there are any errors in the code. This helps ensure that only valid and correct JavaScript is emitted, which can help prevent runtime errors or unexpected behavior.

To enable this setting, simply add “noEmitOnError”: true to your tsconfig.json file. This will tell the compiler to stop emitting JavaScript when it encounters an error. It’s important to note that this setting does not affect compilation speed; it just prevents invalid JavaScript from being generated.

8. Use esModuleInterop to enable interoperability between CommonJS and ECMAScript modules

Using esModuleInterop allows developers to use both CommonJS and ECMAScript modules in the same project without having to manually convert one type of module into another. This is especially useful when working with third-party libraries that may be written using either format, as it eliminates the need for manual conversion.

To enable interoperability between CommonJS and ECMAScript modules, you must set the “esModuleInterop” option to true in your tsconfig file. This will tell the TypeScript compiler to automatically convert any imported CommonJS modules into ECMAScript modules so they can be used alongside other ECMAScript modules.

Additionally, setting this option also enables tree shaking, which helps reduce the size of the final bundle by removing unused code from the output. This is beneficial because it reduces the amount of code that needs to be downloaded by users, resulting in faster page load times.

9. Use allowJs to enable linting of JavaScript files

When allowJs is set to true, TypeScript will lint JavaScript files as if they were TypeScript. This means that any errors or warnings in the code can be caught and fixed before running it. It also allows for better integration between TypeScript and JavaScript projects, since both languages are being treated equally.

The way this works is by using a tool called tsc (TypeScript Compiler). When allowJs is enabled, tsc will parse all of the JavaScript files in the project and check them against the rules specified in tsconfig.json. If there are any issues with the code, tsc will report them so that they can be addressed.

10. Use sourceMap to generate source maps for debugging purposes

Source maps are a way to map the compiled code back to its original source. This is especially useful when debugging, as it allows developers to debug their TypeScript code instead of the generated JavaScript code. With sourceMap enabled in tsconfig, the compiler will generate a separate .map file for each output JavaScript file that contains the mapping information between the two files.

Using sourceMap also helps with performance, since the browser can load the source map and use it to quickly locate the corresponding source code without having to download the entire source file. Additionally, source maps make it easier to identify errors in the source code by providing more detailed stack traces.