maybe this will work

Author: devsnek

api/gist.js

@@ -34,12 +34,17 @@ module.exports = (req, res) => {
   if (req.headers.origin !== 'https://engine262.js.org') {
     return res.status(403).send('403');
   }
+  if (req.method === 'OPTIONS') {
+    res.writeHead(200, { 'Allow': 'OPTIONS, POST' });
+    res.end();
+    return res;
+  }
   if (req.method !== 'POST') {
     return res.status(405).send('405');
   }
   if (!req.body || !req.body.content || !req.body.state) {
     return res.status(400).send('400');
   }
   return createGist(req.body.content, req.body.state)
-    .then((body) => res.status(200).json(body));
+    .then((body) => res.status(200).end(body.id));
 };

now.json

@@ -8,7 +8,7 @@
       "headers": {
         "Access-Control-Allow-Origin": "https://engine262.js.org",
         "Access-Control-Allow-Headers": "content-type",
-        "Access-Control-Allow-Methods": "POST"
+        "Access-Control-Allow-Methods": "OPTIONS, POST"
       }
     },
     {

package.json

@@ -2,5 +2,11 @@
   "name": "server",
   "dependencies": {
     "node-fetch": "^2.6.0"
+  },
+  "devDependencies": {
+    "babel-eslint": "^10.0.3",
+    "eslint": "^6.1.0",
+    "eslint-config-airbnb-base": "^14.0.0",
+    "eslint-plugin-import": "^2.18.2"
   }
 }

src/state.mjs

@@ -91,7 +91,7 @@ export function setState(name, value) {
 document.querySelector('#save-to-gist')
   .addEventListener('click', async () => {
     const s = await state;
-    const body = await fetch('https://engine262-api.snek.now.sh/api/gist', {
+    const id = await fetch('https://engine262-api.snek.now.sh/api/gist', {
       method: 'POST',
       headers: {
         'Content-Type': 'application/json',
@@ -104,8 +104,8 @@ document.querySelector('#save-to-gist')
         },
       }),
 
-    }).then((r) => r.json());
+    }).then((r) => r.text());
     isGist = true;
-    s.set('gist', body.id);
+    s.set('gist', id);
     await updateState();
   });