Eris web app for contract with bytes type data

app.js

// requires
var fs = require ('fs');
var prompt = require('prompt');
var erisC = require('eris-contracts');
var conv = require('binstring');

// NOTE. On Windows/OSX do not use localhost. find the
// url of your chain with:
// docer-machine ls
// and find the docker machine name you are using (usually default or eris).
var erisdbURL = "http://localhost:1337/rpc";

// get the abi and deployed data squared away
var contractData = require('./epm.json');
var idisContractAddress = contractData["deployStorageK"];
var idisAbi = JSON.parse(fs.readFileSync("./abi/" + idisContractAddress));

// properly instantiate the contract objects manager using the erisdb URL
// and the account data (which is a temporary hack)
var accountData = require('./account.json');
var contractsManager = erisC.newContractManagerDev(erisdbURL, accountData);

// properly instantiate the contract objects using the abi and address
var idisContract = contractsManager.newContractFactory(idisAbi).at(idisContractAddress);

// display the current value of idi's contract by calling
// the `get` function of idi's contract
function getValue(callback) {
  idisContract.get(function(error, result){
    if (error) { throw error }
    var hex = result.toString();
    var str = '';
    for (var i = 0; i < hex.length; i += 2)
        str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
    console.log("Previous string: " + str);
    callback();
  });
}

// prompt the user to change the value of idi's contract
function changeValue() {
  prompt.message = "Insert the new string: ";
  prompt.start();
  prompt.get(['value'], function (error, result) {
    if (error) { throw error }
    setValue(result.value)
  });
}

// using eris-contracts call the `set` function of idi's
// contract using the value which was recieved from the
// changeValue prompt
function setValue(value) {
  var newval = conv(value, {out:'hex'});
  idisContract.set(newval, function(error, result){
    if (error) { throw error }
    getValue(function(){});
  });
}

// run
getValue(changeValue);