feat(handler): Headers can be native to fetch

Author: enisdenjo

README.md

@@ -224,12 +224,10 @@ await serve(
       return new Response(null, { status: 404, statusText: 'Not Found' });
     }
 
-    const headers: Record<string, string> = {};
-    req.headers.forEach((value, key) => (headers[key] = value));
     const [body, init] = await handler({
       url: req.url,
       method: req.method,
-      headers,
+      headers: req.headers,
       body: () => req.text(),
       raw: req,
     });

docs/README.md

@@ -17,7 +17,6 @@ graphql-http
 - [ClientOptions](interfaces/ClientOptions.md)
 - [HandlerOptions](interfaces/HandlerOptions.md)
 - [Request](interfaces/Request.md)
-- [RequestHeaders](interfaces/RequestHeaders.md)
 - [RequestParams](interfaces/RequestParams.md)
 - [ResponseInit](interfaces/ResponseInit.md)
 - [ResponseLike](interfaces/ResponseLike.md)
@@ -32,6 +31,7 @@ graphql-http
 - [AuditResult](README.md#auditresult)
 - [ExecutionContext](README.md#executioncontext)
 - [Handler](README.md#handler)
+- [RequestHeaders](README.md#requestheaders)
 - [Response](README.md#response)
 - [ResponseBody](README.md#responsebody)
 - [ResponseHeaders](README.md#responseheaders)
@@ -228,6 +228,14 @@ considered internal errors and you should take care of them accordingly.
 
 ___
 
+### RequestHeaders
+
+Ƭ **RequestHeaders**: { `[key: string]`: `string` \| `string`[] \| `undefined`; `set-cookie?`: `string` \| `string`[]  } \| { `get`: (`key`: `string`) => `string` \| ``null``  }
+
+The incoming request headers the implementing server should provide.
+
+___
+
 ### createHandler
 
 ▸ **createHandler**<`RawRequest`, `Context`\>(`options`): [`Handler`](README.md#handler)<`RawRequest`, `Context`\>

docs/interfaces/Request.md

@@ -46,7 +46,7 @@ ___
 
 ### headers
 
-• `Readonly` **headers**: [`RequestHeaders`](RequestHeaders.md)
+• `Readonly` **headers**: [`RequestHeaders`](../README.md#requestheaders)
 
 ___
 

docs/interfaces/RequestHeaders.md

@@ -29,18 +29,18 @@ import {
  *
  * @category Common
  */
-export interface RequestHeaders {
-  accept?: string | undefined;
-  allow?: string | undefined;
-  'content-type'?: string | undefined;
-  /**
-   * Always an array in Node. Duplicates are added to it.
-   * Not necessarily true for other environments, make sure
-   * to check the type during runtime.
-   */
-  'set-cookie'?: string | string[] | undefined;
-  [key: string]: string | string[] | undefined;
-}
+export type RequestHeaders =
+  | {
+      /**
+       * Always an array in Node. Duplicates are added to it.
+       * Not necessarily true for other environments.
+       */
+      'set-cookie'?: string | string[] | undefined;
+      [key: string]: string | string[] | undefined;
+    }
+  | {
+      get: (key: string) => string | null;
+    };
 
 /**
  * Server agnostic request interface containing the raw request
@@ -374,7 +374,7 @@ export function createHandler<RawRequest = unknown, Context = unknown>(
       ];
     }
 
-    const acceptedMediaType = getAcceptableMediaType(req.headers.accept);
+    const acceptedMediaType = getAcceptableMediaType(getHeader(req, 'accept'));
     if (!acceptedMediaType) {
       return [
         null,
@@ -394,7 +394,7 @@ export function createHandler<RawRequest = unknown, Context = unknown>(
     const [
       mediaType,
       charset = 'charset=utf-8', // utf-8 is assumed when not specified. this parameter is either "charset" or "boundary" (https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Length)
-    ] = (req.headers['content-type'] || '')
+    ] = (getHeader(req, 'content-type') || '')
       .replace(/\s/g, '')
       .toLowerCase()
       .split(';');
@@ -691,3 +691,21 @@ export function makeResponse(
     },
   ];
 }
+
+function getHeader(
+  req: Request<unknown, unknown>,
+  key: 'set-cookie',
+): string[] | null;
+function getHeader(
+  req: Request<unknown, unknown>,
+  key: 'accept' | 'allow' | 'content-type' | string,
+): string | null;
+function getHeader(
+  req: Request<unknown, unknown>,
+  key: string,
+): string | string[] | null {
+  if (typeof req.headers.get === 'function') {
+    return req.headers.get(key);
+  }
+  return Object(req.headers)[key];
+}