part 7 gist - dapp

// package.json
{
  "dependencies": {
    "web3": "0.17.0-alpha",
    "solc": "^0.4.4"
  }
}

// HelloWorld.sol
contract HelloWorld {
  
  function displayMessage() constant returns (string) {
    return "Hello from a smart contract";
  }
  
}

var source = `contract HelloWorld {
  
  function displayMessage() constant returns (string) {
    return "Hello from a smart contract";
  }
  
}
`
var compiled = solc.compile(source)
var bytecode = compiled.contracts[":HelloWorld"].bytecode

//making a contract and deploying it on a test net.
compiled.contracts[":HelloWorld"].interface

//save public interface of contract
var abi = JSON.parse(compiled.contracts[":HelloWorld"].interface)

//create var with contract
var hwContract = web3.eth.contract(abi)

//deploy contract
 var deployed = hwContract.new({
from: web3.eth.accounts[0],
data: compiled.contracts[":HelloWorld"].bytecode,
gas: 4700000,
gasPrice: 5,
}, (error, contract) => {})

//check transaction by hash
web3.eth.getTransaction("0xf59c7b48ba0f4c7dac40f6c2f54b88d4662cd4205eb626ce73ebe9bc5821f4a0")

hwContract.at(_)

//use deployed contract
deployed.displayMessage.call()