MEAN Cookbook

How to do it...

Let's walk through reading and writing headers in Express to implement CORS headers and language locale preferences using the Accept-Languages header:

1. First, in our /routes/api.js route configuration, we will add a new route for any incoming options requests. We will want to add this route before any other API routes in this configuration file so that it is handled first:

...router.options('*', function (req, res, next) {  res.header('Access-Control-Allow-Origin', '*');  res.header('Access-Control-Allow-Methods',        'GET,PUT,POST,DELETE,PATCH,OPTIONS');  res.header('Access-Control-Allow-Headers', 'Content-    Type, Authorization, Content-Length, X-Requested-    With');  res.send(200);});...

2. Now, when API requests make pre-flight requests ...