Web3 module
web3.js works with any Ethereum node, which exposes an RPC(remote procedure call) layer.
It is a JavaScript library that implements the Ethereum JSON RPC. That is, the protocol that we will use to talk to an Ethereum node (in this case, testrpc). To install it, just run:
npm install -g [email protected]
https://github.com/ethereum/wiki/wiki/JavaScript-API
First of all, you need to connect Web3 with your local testing node you are running withtestrpc.In order to do that, we will ask Web3 to use a localhost provider. Let’s open a node console and input following lines:
Web3 = require('web3')
provider = new Web3.providers.HttpProvider("http://localhost:8545")
web3 = new Web3(provider)
Web3 Versioning
We use the newer version of Web3 in order to support for promises.