Add GraphQL Helix example

Author: danielrearden

src/content/code/language-support/javascript/server/graphql-helix.md

@@ -6,4 +6,79 @@ github: contrawork/graphql-helix
 npm: "graphql-helix"
 ---
 
+To run a hello world server with GraphQL Helix:
 
+```bash
+npm install graphql graphql-helix express
+```
+
+Then run `node server.js` with this code in `server.js`:
+
+```js
+const express = require('express')
+const {
+  GraphQLObjectType,
+  GraphQLSchema,
+  GraphQLString
+} = require('graphql');
+const {
+  getGraphQLParameters,
+  processRequest,
+  renderGraphiQL,
+  shouldRenderGraphiQL
+} = require('graphql-helix');
+
+const schema = new GraphQLSchema({
+  query: new GraphQLObjectType({
+    name: 'Query',
+    fields: {
+      hello: {
+        type: GraphQLString,
+        resolve: () => 'Hello world!',
+      },
+    },
+  }),
+});
+
+const app = express();
+
+app.use(express.json());
+
+app.use('/graphql', async (req, res) => {
+  const request = {
+    body: req.body,
+    headers: req.headers,
+    method: req.method,
+    query: req.query,
+  };
+
+  if (shouldRenderGraphiQL(request)) {
+    res.send(renderGraphiQL());
+  } else {
+    const { operationName, query, variables } = getGraphQLParameters(request);
+
+    const result = await processRequest({
+      operationName,
+      query,
+      variables,
+      request,
+      schema,
+    });
+
+    if (result.type === 'RESPONSE') {
+      result.headers.forEach(({ name, value }) => res.setHeader(name, value));
+      res.status(result.status);
+      res.json(result.payload);
+    } else {
+    // graphql-helix also supports subscriptions and incremental delivery (i.e. @defer and @stream directives)
+    // out of the box. See the repo for more complete examples that also implement those features.
+    }
+  }
+});
+
+app.listen(4000, () =>
+  console.log('Now browse to http://localhost:4000/graphql');
+)
+```
+
+This example uses Express, but GraphQL Helix is framework- and runtime-agnostic -- it can run in Node, Deno and the browser. GraphQL Helix provides you with a handful of utility functions to build your own HTTP server but leaves the ultimate implementation details up to you.