Merge pull request #9 from signalnerve/kristian/cors

Add CORS support for GraphQL requests

src/index.js

@@ -1,23 +1,45 @@
 const apollo = require('./handlers/apollo')
 const playground = require('./handlers/playground')
+const setCors = require('./utils/setCors')
 
 const graphQLOptions = {
   // Set the path for the GraphQL server
   baseEndpoint: '/',
+
   // Set the path for the GraphQL playground
   // This option can be removed to disable the playground route
   playgroundEndpoint: '/___graphql',
+
   // When a request's path isn't matched, forward it to the origin
   forwardUnmatchedRequestsToOrigin: false,
+
   // Enable debug mode to return script errors directly in browser
   debug: false,
+
+  // Enable CORS headers on GraphQL requests
+  // Set to `true` for defaults (see `utils/setCors`),
+  // or pass an object to configure each header
+  cors: true,
+  // cors: {
+  //   allowCredentials: 'true',
+  //   allowHeaders: 'Content-type',
+  //   allowOrigin: '*',
+  //   allowMethods: 'GET, POST, PUT',
+  // },
 }
 
 const handleRequest = request => {
   const url = new URL(request.url)
   try {
     if (url.pathname === graphQLOptions.baseEndpoint) {
-      return apollo(request, graphQLOptions)
+      const response =
+        request.method === 'OPTIONS'
+          ? new Response('', { status: 204 })
+          : await apollo(request, graphQLOptions)
+      if (graphQLOptions.cors) {
+        setCors(response, graphQLOptions.cors)
+      }
+      return response
     } else if (
       graphQLOptions.playgroundEndpoint &&
       url.pathname === graphQLOptions.playgroundEndpoint

src/utils/setCors.js

@@ -0,0 +1,20 @@
+const setCorsHeaders = (response, config) => {
+  const corsConfig = config instanceof Object ? config : false
+
+  response.headers.set(
+    'Access-Control-Allow-Credentials',
+    corsConfig ? corsConfig.allowCredentials : 'true',
+  )
+  response.headers.set(
+    'Access-Control-Allow-Headers',
+    corsConfig ? corsConfig.allowHeaders : 'application/json, Content-type',
+  )
+  response.headers.set(
+    'Access-Control-Allow-Methods',
+    corsConfig ? corsConfig.allowMethods : 'GET, POST',
+  )
+  response.headers.set('Access-Control-Allow-Origin', corsConfig ? corsConfig.allowOrigin : '*')
+  response.headers.set('X-Content-Type-Options', 'nosniff')
+}
+
+module.exports = setCorsHeaders