If I have generated only typescript type declaration files from a project that am I importing, how can I make the types work?

If I have generated only typescript type declaration files from a project that am I importing, how can I make the types work? The types do not seem to include any mention of the package name so I assume some form of mapping would be required.

You’re correct that simply importing declaration files (.d.ts files) wouldn’t automatically work with your project unless they are properly configured. Here’s what you need to do to make the types work:

1. Mapping with tsconfig.json:

  • Locate your tsconfig.json file: This is the configuration file for your TypeScript compiler.
  • Add the compilerOptions property: Under this property, add "baseUrl" and "paths" options.
  • Set baseUrl: This option specifies the base directory where the compiler should start resolving modules. Set it to the directory containing the imported type declaration files.
  • Set paths: This option maps module names to their corresponding file paths. Define a mapping for the package you’re importing. Here’s the syntax:
JSON
"paths": {
  "your-package-name/*": ["path/to/your-package-name/*.d.ts"]
}

2. Using Type Aliases (Optional):

Even with the mapping, the imported types might not have the same names as in the original package. To address this:

  • Define type aliases in your own code for the imported types. This allows you to use familiar names for the types while still benefiting from type safety.

Example:

Assuming you’re importing a package named my-package:

tsconfig.json:

JSON
{
  "compilerOptions": {
    "baseUrl": "src/types", // Assuming your types are in a "types" folder
    "paths": {
      "my-package/*": ["../node_modules/my-package/*.d.ts"]
    }
  }
}

Your code:

TypeScript
// Assuming the type declaration defines an interface called "MyComponent"
import type { MyComponent } from "my-package";

// Define type alias
type MyCustomComponent = MyComponent;

// Use the alias like any other type
const myComponent: MyCustomComponent = { /* ... */ };

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