MongoDB has a simple web based administrative port at 28017 by default.
There is no HTTP access at the default port of 27017 (which is what the error message is trying to suggest). The default port is used for native driver access, not HTTP traffic.
To access MongoDB, you'll need to use a driver like the MongoDB native driver for NodeJS. You won't "POST" to MongoDB directly (but you might create a RESTful API using express which uses the native drivers). Instead, you'll use a wrapper library that makes accessing MongoDB convenient. You might also consider using Mongoose (which uses the native driver) which adds an ORM-like model for MongoDB in NodeJS.
If you can't get to the web interface, it may be disabled. Normally, I wouldn't expect that you'd need it for doing development unless you're checking logs and such.