I would like to use coinbase as a payment gateway. likewise online retailers payments done can i use it like that? then help me to do it with Node.js
This is the un-official library for coinbase api that is in node.js https://github.com/otakup0pe/nodecoinbase. Coinbase has a very nice documentation with their api here: https://coinbase.com/api/doc/1.0.html and you might be interested in the transactions. Also if you just planning to sell items, you can just use the "Bitcoins Accepted Here" button VIA the Merchant tools > Tools page.