Send ERC20 token with web3

Question

I'm currently using 0.2x.x version of Web3 Javascript API. I deployed my custom ERC20 token by creating smart contract in solidity (on REMIX IDE). I installed the MetaMask and had a test on https://wallet.ethereum.org/ to send some custom ERC token to another my account. It worked well. I want to add the 'send custom ERC20 Token' function in my javascript code using Web3.

Here is my code below.

var http = require('http');
var Web3 = require('web3');
var Tx = require('ethereumjs-tx');

var abi = [{"...."}]; 
var data = '0x00..';
var contract_addr = '0x00..';
var owner = '0x00..';

var web3 = new Web3(new Web3.providers.HttpProvider("https://ropsten.infura.io/")); 
web3.eth.getBlock("latest", (error, result) => {
//console.log('error:', error);
//console.log('results', result);
});

var myContract = web3.eth.contract(abi);
var myContractInstance = myContract.at(address);

eb3.eth.getDefaultAccount = owner;
var defaultAccount = web3.eth.getDefaultAccount;
console.log('DefaultAccount => ', defaultAccount); 

var total = myContractInstance.totalSupply();
var balance = myContractInstance.balanceOf(defaultAccount);

console.log('DefulatAccount total => ',total);
console.log('DefaultAccount balance => ',balance);

var to = '0x00..';
var isAddress = web3.isAddress(to);

console.log('isAddress(to) => ',isAddress);
console.log('balanceOf(to) => ',myContractInstance.balanceOf(to));

I'm working on the 'Ropsten Testnet' and I sent some 'ether' for test using sendRawTransaction(). But what I want to do is just sending my custom ERC20 token. not the ether. How can I send my own token in this script? I have no idea. I tried to use sendTransaction() like below.

var rawTx = {
    from : defaultAccount,
    nonce : nonceHex,
    gasPrice : gasPriceHex,
    gas : gasHex,
    to : to,
    value : 100,
    data : data
};

web3.eth.sendTransaction(rawTx, function(err, transactionHash) {
    if (!err)
        console.log('transactionHash => ',transactionHash);
    else
        console.log(err);
});

I continuously received the error.

Error: Invalid JSON RPC response: ""
at Object.InvalidResponse (/Users/rachel/dev/test/node_modules/web3/lib/web3/errors.js:38:16)
at XMLHttpRequest.request.onreadystatechange (/Users/rachel/dev/test/node_modules/web3/lib/web3/httpprovider.js:119:24)
at XMLHttpRequestEventTarget.dispatchEvent (/Users/rachel/dev/test/node_modules/xhr2/lib/xhr2.js:64:18)
at XMLHttpRequest._setReadyState (/Users/rachel/dev/test/node_modules/xhr2/lib/xhr2.js:354:12)
at XMLHttpRequest._onHttpResponseEnd (/Users/rachel/dev/test/node_modules/xhr2/lib/xhr2.js:509:12)
at IncomingMessage.<anonymous> (/Users/rachel/dev/test/node_modules/xhr2/lib/xhr2.js:469:24)
at emitNone (events.js:111:20)
at IncomingMessage.emit (events.js:208:7)
at endReadableNT (_stream_readable.js:1056:12)
at _combinedTickCallback (internal/process/next_tick.js:138:11)

I really can't understand what is wrong with it. Please let me know some way to deal with this. Thanks!

Answer 1

Error: Invalid JSON RPC response: "" means web3 cant connect to rpc node. Try running one with ::

-for testnet

geth --testnet --rpc --rpcaddr 127.0.0.1 --rpcport 8545 --rpccorsdomain '*' --rpcapi personal,admin,db,eth,net,web3,miner,shh,txpool,debug --ws --wsaddr 127.0.0.1 --wsport 8546 --wsorigins '*' --wsapi personal,admin,db,eth,net,web3,miner,shh,txpool,debug --maxpeers 25 0 --gasprice 100

-for mainnet

geth --rpc --rpcaddr 127.0.0.1 --rpcport 8545 --rpccorsdomain '*' --rpcapi personal,admin,db,eth,net,web3,miner,shh,txpool,debug --ws --wsaddr 127.0.0.1 --wsport 8546 --wsorigins '*' --wsapi personal,admin,db,eth,net,web3,miner,shh,txpool,debug --maxpeers 25 0 --gasprice 100

Now in your case (using infura testnet node), get a id from infura.io. It should be like this ::

https://ropsten.infura.io/id