In this article, we analyze TypeDoc usage in @vercel/edge package.

I found a file named typedoc.json, got me wondering what’s TypeDoc and a quick google search helped me find TypeDoc website.

So what’s TypeDoc?

TypeDoc

TypeDoc converts comments in TypeScript source code into rendered HTML documentation or a JSON model. It is extensible and supports a variety of configurations. Available as a CLI or Node module.

TypeDoc documentation is comprehensive. Let’s now focus on how this is used in @vercel/edge.

typedoc.json configuration in @vercel/edge:

The below code is picked from packages/edge/typedoc.json.

{
 "$schema": "https://typedoc.org/schema.json",
 "entryPoints": ["src/index.ts"],
 "plugin": ["typedoc-plugin-markdown", "typedoc-plugin-mdn-links"],
 "out": "docs",
 "githubPages": false,
 "gitRevision": "main",
 "readme": "none",
 "hideBreadcrumbs": true
}

You require this configuration when you are using CLI to run TypeDoc.

Pay attention to “out” value, it is “docs”, it is a good thing that we have already docs generated for @vercel/edge package

ModifiedRequest interface:

Let’s pick ModifiedRequest interface found in middleware-helpers.ts

export interface ModifiedRequest {
 /**
 * If set, overwrites the incoming headers to the origin request.
 *
 * This is useful when you want to pass data between a Middleware and a
 * Serverless or Edge Function.
 *
 * @example
 * <caption>Add a `x-user-id` header and remove the `Authorization` header</caption>
 *
 * ```ts
 * import { rewrite } from '@vercel/edge';
 * export default async function middleware(request: Request): Promise<Response> {
 * const newHeaders = new Headers(request.headers);
 * newHeaders.set('x-user-id', 'user_123');
 * newHeaders.delete('authorization');
 * return rewrite(request.url, {
 * request: { headers: newHeaders }
 * })
 * }
 * ```
 */
 headers?: Headers;
}

This interface has a comment added that is picked by TypeDoc and is made available in docs at edge/docs/interfaces/ModifiedRequest.md

But what’s the command this package uses to initiate documentation generation? It can be found in package.json

"build:docs": "typedoc && node scripts/fix-links.js && prettier - write docs/**/*.md docs/*.md",

You can see prettier is applied on the docs folder.

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References:

1. https://github.com/vercel/vercel/blob/main/packages/edge/typedoc.jso

2. https://github.com/TypeStrong/typedoc

3. https://typedoc.org/

4. https://github.com/vercel/vercel/blob/main/packages/edge/docs

5. https://github.com/vercel/vercel/blob/main/packages/edge/docs/interfaces/ModifiedRequest.md

6. https://github.com/vercel/vercel/blob/main/packages/edge/src/middleware-helpers.ts#L1