TypeScript

Pages Functions supports TypeScript. Author any files in your /functions directory with a .ts extension instead of a .js extension to start using TypeScript.

To add the runtime types to your project, run:

$ npm install --save-dev typescript @cloudflare/workers-types

Then configure the runtime types by creating a functions/tsconfig.json file:

functions/tsconfig.json
{
  "compilerOptions": {
    "target": "esnext",
    "module": "esnext",
    "lib": ["esnext"],
    "types": ["@cloudflare/workers-types"]
  }
}

If you already have a tsconfig.json at the root of your project, you may wish to explicitly exclude the /functions directory to avoid conflicts. To exclude the /functions directory:

tsconfig.json
{
  "include": ["src/**/*"],
  "exclude": ["functions/**/*"],
  "compilerOptions": {

  }
}

Pages Functions can be typed using the PagesFunction type. This type accepts an Env parameter. To use the env parameter:

functions/example.ts
interface Env {
	KV: KVNamespace;
}

export const onRequest: PagesFunction<Env> = async (context) => {
	const value = await context.env.KV.get('example');
 	return new Response(value);
}