Transfer ERC20 tokens in nodejs

After the previous transfer of eth, this time we will continue to see how to transfer ERC20 tokens.

Install dependencies and initialize web3#

I won't go into detail here. If you don't know how to initialize web3, you can refer to one of my previous articles.

Initialize the contract object Contract#

Last time we created a start method. This time we will create a startContract method inside it, and replace the code below with the execution of the startContract method.

const startContract = async () => {
    let currentAddress = '0xe208D2fB37df02061B78848B83F02b4AD33540e4'
    let toAddress = '0x3EcAa09DD6B8828607bba4B1d7055Ea1143f8B94'
  
  // This time we still choose uni on the goerli test chain for the token
    const uniContractAddress = '0x1f9840a85d5af5bf1d1762f925bdaddc4201f984'    // uni erc20 token contract address

    const uniswapAbi = []	// uni's abi information, you can find it yourself, or you can check my web3 learning notes for specific search methods
    
    const uniToken = new web3.eth.Contract(uniswapAbi, uniContractAddress)
    
}
startContract()

This way we have the contract object Contract.

Initialize parameters#

Let's prepare some parameters needed for the transaction.

const privateKey = Buffer.from('Your wallet private key', 'hex')
// Before setting the amount, we need to get the precision of the token currency. Here the decimals value is 18, which means 18 digits.
const decimals = await uniToken.methods.decimals().call()

// amount = transfer amount * decimals, here we transfer 1 uni token
const amount = web3.utils.toHex(1 * Math.pow(10, decimals))

const count = await web3.eth.getTransactionCount(currentAddress)

const txParams = {
  from: currentAddress,
  to: uniContractAddress,
  gasPrice: web3.utils.toHex(web3.utils.toWei('10', 'gwei')),
  gasLimit: web3.utils.toHex(210000),
  value: web3.utils.toHex(0),
  data: uniToken.methods.transfer(toAddress, amount).encodeABI(),
  nonce: web3.utils.toHex(count)
}

const tx = new EthereumTx(txParams, {
  chain: 'goerli'
})

tx.sign(privateKey)

Now we have the required parameters and have signed the key.

The above ethereumjs-tx signature scheme uses ethereumjs-common by default, which has:

mainnet
ropsten
rinkeby
kovan
goerli (final configuration since v1.1.0)
You can directly sign for these chains. For other chains, you need to require ethereumjs-common yourself.

const  Common = require('ethereumjs-common').default
const blockchain = Common.forCustomChain(
    'mainnet', {
        name: 'Fantom Opera',
        networkId: 250,
        chainId: 250
    },
    'petersburg'
)

const tx = new EthereumTx(txParams, {
    common: blockchain
})

tx.sign(privateKey)

Send transaction#

web3.eth.sendSignedTransaction('0x' + tx.serialize().toString('hex'))
  .on('transactionHash', console.log)
  .catch(err => {
  	console.log({err});
  })

This way we have already sent the token.