Introduction

Suppose you wish to purchase TRC tokens using the TRX balance from your TRX wallet. You can either do this using traditional exchanges otherwise provide user option to buy trc tokens for trx in the dapp itself to avoid the log route.

Explanation

Initiate nodejs project

npm init

Install tronweb

npm install -g tronweb

Create index.js file

touch index.js

Define required parameters

const TronWeb = require('tronweb');
const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider('https://api.trongrid.io');
const solidityNode = new HttpProvider('https://api.trongrid.io');
const eventServer = 'https://api.trongrid.io';
const privateKey = 'Your Private Key Here';

Create tronweb object

const tronWeb = new TronWeb(
    fullNode,
    solidityNode,
    eventServer,
    privateKey,
);

Create params and function to trade

const param = {
  exchangeID:5,          //Exchange ID Number
  tokenName:"_",         //Token name for TRX
  sold:100000000,        //TRX amount sold. Must be in SUN denomination.
  expected:1,            //Assigned as 1 to keep wide limit, like market order
  privKey:'Your Private Key Here',
}

async function trade(param){
  try {
    // Performs the trade between Token and TRX
    const tradeobj = await tronWeb.transactionBuilder.tradeExchangeTokens(exchangeID = param.exchangeID,
    tokenName = param.tokenName,
    tokenAmountSold = param.sold,
    tokenAmountExpected = param.expected,
    ownerAddress = "Your TRX Wallet Address Here - in Hex String");

    // Signing the transaction
    const signedtxn = await tronWeb.trx.sign(tradeobj, param.privKey);

    // Broadcasting the transaction
    const receipt = await tronWeb.trx.sendRawTransaction(signedtxn);
    console.log(receipt)
  }
  catch(err) {
    console.log(err);
  };
};

trade(param); // Execute the function

Complete Code:

const TronWeb = require('tronweb');
const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider('https://api.trongrid.io');
const solidityNode = new HttpProvider('https://api.trongrid.io');
const eventServer = 'https://api.trongrid.io';
const privateKey = 'Your Private Key Here';

// Create tronWeb object defining Node addresses
const tronWeb = new TronWeb(
    fullNode,
    solidityNode,
    eventServer,
    privateKey,
);

// Create param object that defines all the API input parameters
const param = {
  exchangeID:5,          //Exchange ID Number
  tokenName:"_",         //Token name for TRX
  sold:100000000,        //TRX amount sold. Must be in SUN denomination.
  expected:1,            //Assigned as 1 to keep wide limit, like market order
  privKey:'Your Private Key Here',
}

async function trade(param){
  try {
    // Performs the trade between Token and TRX
    const tradeobj = await tronWeb.transactionBuilder.tradeExchangeTokens(exchangeID = param.exchangeID,
    tokenName = param.tokenName,
    tokenAmountSold = param.sold,
    tokenAmountExpected = param.expected,
    ownerAddress = "Your TRX Wallet Address Here - in Hex String");

    // Signing the transaction
    const signedtxn = await tronWeb.trx.sign(tradeobj, param.privKey);

    // Broadcasting the transaction
    const receipt = await tronWeb.trx.sendRawTransaction(signedtxn);
    console.log(receipt)
  }
  catch(err) {
    console.log(err);
  };
};

trade(param); // Execute the function