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TRC21 Exchange/Wallet

This tutorial is a guide for a developer who wants to know how to integrate TRC21 token to applications (e.g., wallet, exchange)

Smart Contract ABI: TRC21.json

TRC21 Contract Interface:

function totalSupply() external view returns (uint256);
function balanceOf(address who) external view returns (uint256);
function estimateFee(uint256 value) external view returns (uint256);
function issuer() external view returns (address);
function allowance(address owner, address spender) external view returns (uint256);
function transfer(address to, uint256 value) external returns (bool);
function approve(address spender, uint256 value) external returns (bool);
function transferFrom(address from, address to, uint256 value) external returns (bool);

event Transfer(address indexed from, address indexed to, uint256 value);
event Approval(address indexed owner, address indexed spender, uint256 value);
event Fee(address indexed from, address indexed to, address indexed issuer, uint256 value);

Refer to TRC21 Specification

TomoChain provides RPC APIs. So you can use Web3 library to directly call the functions in the smart contract.

You can follow the steps below to interact with the smart contract by using Web3 library and NodeJS.

Init Web3 provider

At the first step, you need init Web3 provider by connecting TomoChain Fullnode RPC endpoint.

You can take a look to TomoChain Networks page to get the details of Testnet/Mainnet network information.

const Web3 = require('web3')
const web3 = new Web3('https://rpc.tomochain.com')
const chainId = 88

Unlock wallet

You need to unlock the wallet before interact TRC21 contract

Example

// Unlock wallet by private key
const account = web3.eth.accounts.privateKeyToAccount(pkey)
const holder = account.address
web3.eth.accounts.wallet.add(account)
web3.eth.defaultAccount = holder

Init Web3 TRC21 Contract

const trc21Abi = require('./TRC21.json')
const address = '[enter_your_contract_address]'
const trc21 = new web3.eth.Contract(trc21Abi,
        address, {gasPrice: 250000000, gas: 2000000 })

Note: you can get TRC21.json here

Check balance

You need to call function balanceOf() from TRC21 contract to check your token balance for an address.

Example

trc21.methods.balanceOf(holder).call()
.then((result) => {
    console.log(result)
}).catch(e => console.log(e))

Estimate fee

Before sending tokens, we need to check TX fee by calling estimateFee function in TRC21 smart contract.

Example

trc21.methods.estimateFee().call()
.then((result) => {
    console.log(result)
}).catch(e => console.log(e))

Note: this fee is amount token you need to pay to send TRC21 token that applied TomoZ

Transfer token

Token holder needs to call function transfer to send token to an address

Example

// send 500000000000000000000 tokens to this address (e.g decimals 18)
const to = "0xf8ac9d5022853c5847ef75aea0104eed09e5f402"
trc21.methods.transfer(to, '500000000000000000000').send({
    from: holder,
    gas: 2000000,
    gasPrice: 250000000,
    chainId: chainId
})
.then((result) => {
    console.log(result)
}).catch(e => console.log(e))

You can take a look to this example Transfer TRC21 token