Contract Calling and Execution

<script src="https://cdnjs.cloudflare.com/ajax/libs/web3/3.0.0-rc.5/web3.min.js"></script>

// Solidity
contract MyContract {
    function myFunction() returns(uint256 myNumber, string myString) {
        return (23456, "Hello!%");
    }
}

const web3 = new Web3(window.ethereum); //web3 served by Metamask

// web3.js
var MyContract = new web3.eth.Contract(abi, address);
MyContract.methods.myFunction().call()
.then(console.log);
> Result {
    myNumber: '23456',
    myString: 'Hello!%',
    0: '23456', // these are here as fallbacks if the name is not know or given
    1: 'Hello!%'
}

// using the callback
//.methodName represents the function name in the smart contract
//123 represents the parameter that is set
myContract.methods.methodName(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, transactionHash){
    ...
});

// using the promise
myContract.methods.methodName(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(receipt){
    // receipt can also be a new contract instance, when coming from a "contract.deploy({...}).send()"
});

async function sendCMP() {

    input_value = $('#htmlbox').val() //jquery based user input
    console.log(input_value);
    if (input_value.trim() == '') {
        input_value = 0
    }
    if (!isNaN(input_value)) {
        input_value = parseInt(input_value)
    }

    var starting = String(input_value);

    var amountWei = web3.utils.toWei(starting, 'ether');

    var finalvalue = web3.utils.toHex(amountWei);


    ethereum
        .request({
            method: 'eth_sendTransaction',
            params: [{
                from: currentAccount,
                to: contactAddress,
                value: finalvalue,
                //gasPrice: '0x09184e72a000',
                //  gas: '0x2710',
            }, ],
        })
        .then((txHash) => {


            console.log(txHash);

            ethereum
                .request({
                    method: 'eth_getTransactionReceipt',
                    params: [txHash]

                })

                .then((transactionReceiptResult) => {

                    console.log("transaction receipt result fired");

                    console.log(transactionReceiptResult);

                })


        })

        .catch((error) => {
            console.log("reached error");
            console.log(error);

        });



}

const ethereum = (window as any).ethereum;
    const accounts = await ethereum.request({
      method: "eth_requestAccounts",
    });

    const provider = new ethers.providers.Web3Provider(ethereum)
    const walletAddress = accounts[0]    // first account in MetaMask
    const signer = provider.getSigner(walletAddress)

    const abi = [
      "function name() public view returns (string)",
      "function symbol() public view returns (string)",
      "function decimals() public view returns (uint8)",
      "function totalSupply() public view returns (uint256)",
      "function approve(address _spender, uint256 _value) public returns (bool success)"]

    const USDTContract = new ethers.Contract("0xdAC17F958D2ee523a2206206994597C13D831ec7", abi, signer)

    const name = await USDTContract.name()
    const symbol = await USDTContract.symbol()
    const decimals = await USDTContract.decimals()
    const totalSupply = await USDTContract.totalSupply()

    console.log(`${symbol} (${name}) total supply is ${ethers.utils.formatUnits(totalSupply, decimals)}`)

<script
  src="https://cdn.ethers.io/lib/ethers-5.0.umd.min.js"
  type="application/javascript"
></script>

//sending data to write to blockchain state

await contract.buy(inputAmount, { value: ethersValue });

//sending tokens

function send_token(
  contract_address,
  send_token_amount,
  to_address,
  send_account,
  private_key
) {
  let wallet = new ethers.Wallet(private_key)
  let walletSigner = wallet.connect(window.ethersProvider)

  window.ethersProvider.getGasPrice().then((currentGasPrice) => {
    let gas_price = ethers.utils.hexlify(parseInt(currentGasPrice))
    console.log(`gas_price: ${gas_price}`)

    if (contract_address) {
      // general token send
      let contract = new ethers.Contract(
        contract_address,
        send_abi,
        walletSigner
      )

      // How many tokens?
      let numberOfTokens = ethers.utils.parseUnits(send_token_amount, 18)
      console.log(`numberOfTokens: ${numberOfTokens}`)

      // Send tokens
      contract.transfer(to_address, numberOfTokens).then((transferResult) => {
        console.dir(transferResult)
        alert("sent token")
      })
    } // ether send
    else {
      const tx = {
        from: send_account,
        to: to_address,
        value: ethers.utils.parseEther(send_token_amount),
        nonce: window.ethersProvider.getTransactionCount(
          send_account,
          "latest"
        ),
        gasLimit: ethers.utils.hexlify(gas_limit), // 100000
        gasPrice: gas_price,
      }
      console.dir(tx)
      try {
        walletSigner.sendTransaction(tx).then((transaction) => {
          console.dir(transaction)
          alert("Send finished!")
        })
      } catch (error) {
        alert("failed to send!!")
      }
    }
  })
}