Generate and combine type definitions in TypeScript monorepo

Generate and Combine Type Definitions in TypeScript Monorepo

When working with a TypeScript monorepo, managing type definitions can become a complex task. In this blog post, we will explore different approaches to generate and combine type definitions in a TypeScript monorepo.

Approach 1: Using tsconfig.json

One way to generate and combine type definitions is by leveraging the tsconfig.json file. By configuring the include property, we can specify the directories to include for type definition generation.

Here’s an example of a tsconfig.json file:

{
  "compilerOptions": {
    "declaration": true,
    "outDir": "./dist",
    "composite": true
  },
  "include": [
    "packages/**/src"
  ]
}

In this example, we have a monorepo with multiple packages, and we want to generate type definitions for the source files in each package. By setting the declaration option to true and specifying the outDir, TypeScript will generate declaration files (.d.ts) in the specified output directory.

To combine the generated type definitions, we can use a tool like tsc (TypeScript compiler) with the --declaration flag. This will compile the project and generate a single declaration file that includes all the type definitions from the monorepo.

Approach 2: Using TypeScript Project References

Another approach to generate and combine type definitions in a TypeScript monorepo is by using TypeScript project references. This feature allows us to reference other projects within the monorepo and build them together.

To set up project references, we need to create a tsconfig.json file for each package in the monorepo. In each package’s tsconfig.json, we can specify the references to other packages.

Here’s an example of a package’s tsconfig.json file:

{
  "extends": "../../tsconfig.base.json",
  "compilerOptions": {
    "outDir": "./dist",
    "composite": true
  },
  "references": [
    {
      "path": "../package1"
    },
    {
      "path": "../package2"
    }
  ],
  "include": [
    "./src"
  ]
}

In this example, the package references package1 and package2. When building the package, TypeScript will also build the referenced packages and combine their type definitions into a single declaration file.

Conclusion

Generating and combining type definitions in a TypeScript monorepo can be achieved through different approaches. By leveraging the tsconfig.json file or TypeScript project references, we can effectively manage and consolidate type definitions across multiple packages.

Remember to choose the approach that best suits your project’s needs and structure.

Happy coding!

Generate and combine type definitions in TypeScript monorepo