Files for Walkthrough of Transferring data to Matic chain (https://docs.matic.network/docs/develop/advanced/transfer-data)

Receiver.sol

// receiver.sol

pragma solidity ^0.5.11;

// IStateReceiver represents interface to receive state
interface IStateReceiver {
  function onStateReceive(uint256 stateId, bytes calldata data) external;
}

contract receiver {

  uint public lastStateId;
  bytes public lastChildData;

  function onStateReceive(uint256 stateId, bytes calldata data) external {
    lastStateId = stateId;
    lastChildData = data;
	}

}

ReceiverABI.json

[
	{
		"constant": false,
		"inputs": [
			{
				"internalType": "uint256",
				"name": "stateId",
				"type": "uint256"
			},
			{
				"internalType": "bytes",
				"name": "data",
				"type": "bytes"
			}
		],
		"name": "onStateReceive",
		"outputs": [],
		"payable": false,
		"stateMutability": "nonpayable",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [],
		"name": "lastChildData",
		"outputs": [
			{
				"internalType": "bytes",
				"name": "",
				"type": "bytes"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [],
		"name": "lastStateId",
		"outputs": [
			{
				"internalType": "uint256",
				"name": "",
				"type": "uint256"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	}
]

Sender.sol

// sender.sol
pragma solidity ^0.5.11;
contract IStateSender {
  function syncState(address receiver, bytes calldata data) external;
  function register(address sender, address receiver) public;
}
contract sender {
  address public stateSenderContract = 0x22E1f5aa1BA9e60527250FFeb35e30Aa2913727f;
  address public receiver = 0x83bB46B64b311c89bEF813A534291e155459579e;
  
  uint public states = 0;
  function sendState(bytes calldata data) external {
    states = states + 1 ;
    IStateSender(stateSenderContract).syncState(receiver, data);
  }
  
}

SenderABI.json

[
	{
		"constant": false,
		"inputs": [
			{
				"internalType": "bytes",
				"name": "data",
				"type": "bytes"
			}
		],
		"name": "sendState",
		"outputs": [],
		"payable": false,
		"stateMutability": "nonpayable",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [],
		"name": "receiver",
		"outputs": [
			{
				"internalType": "address",
				"name": "",
				"type": "address"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [],
		"name": "states",
		"outputs": [
			{
				"internalType": "uint256",
				"name": "",
				"type": "uint256"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	},
	{
		"constant": true,
		"inputs": [],
		"name": "stateSenderContract",
		"outputs": [
			{
				"internalType": "address",
				"name": "",
				"type": "address"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	}
]

test.js

// test.js

const Web3 = require('web3')
const Network = require("@maticnetwork/meta/network")

const network = new Network ('testnet', 'v3')

const main = new Web3(network.Main.RPC)
const matic = new Web3 (network.Matic.RPC)

let privateKey = `0x...`
matic.eth.accounts.wallet.add(privateKey)
main.eth.accounts.wallet.add(privateKey)

let receiverAddress = `0x83bB46B64b311c89bEF813A534291e155459579e`
let receiverABI = ``
let senderAddress = `0xf428d353aBdb6fdFf9E5E713f1Ec403cD15d0975`
let senderABI = ``



let sender = new main.eth.Contract(JSON.parse(senderABI), senderAddress)
let receiver = new matic.eth.Contract(JSON.parse(receiverABI), receiverAddress)

// data to sync
function getData(string) {
  let data = matic.utils.asciiToHex(string);
  return data
}

function getString(data) {
  let string = matic.utils.hexToAscii(data);
  return string
}

// console.log(getData('Sending a state sync! :) '))

async function sendData (data) {
  let r = await sender.methods
    .sendState (getData(data))
    .send({
      from: main.eth.accounts.wallet[0].address,
      gas: 8000000
    })
  console.log('sent data from root, ', r.transactionHash)
}

async function checkSender () {
  let r = await sender.methods
    .states()
    .call()
  console.log('number of states sent from sender: ', r)
}

async function checkReceiver () {
  let r = await receiver.methods
    .lastStateId()
    .call()
  let s = await receiver.methods
    .lastChildData()
    .call()
  console.log('last state id: ', r, 'and last data: ', s)
  console.log('interpreted data: ', getString(s))
}

async function test() {
	await sendData ('Hello World !')
	await checkSender ()
	// add a timeout here to allow time gap for the state to sync
	await checkReceiver ()
}

test()