Network Gas Fee: How to Fetch It Using Node.js

git clone https://github.com/rick001/crypto-transaction-api-nodejs.git
cd crypto-transaction-api-nodejs
npm install

ALCHEMY_MAINNET_URL=https://eth-mainnet.alchemyapi.io/v2/YOUR_ALCHEMY_PROJECT_ID
ALCHEMY_SEPOLIA_URL=https://eth-sepolia.alchemyapi.io/v2/YOUR_ALCHEMY_PROJECT_ID
NETWORK=mainnet

const { Web3 } = require('web3');
require('dotenv').config();

const ALCHEMY_MAINNET_URL = process.env.ALCHEMY_MAINNET_URL;
const ALCHEMY_SEPOLIA_URL = process.env.ALCHEMY_SEPOLIA_URL;
const NETWORK = process.env.NETWORK;

const alchemyUrl = NETWORK === 'testnet' ? ALCHEMY_SEPOLIA_URL : ALCHEMY_MAINNET_URL;

const web3 = new Web3(new Web3.providers.HttpProvider(alchemyUrl));

async function getEthereumGas() {
    try {
        const gasPriceWei = await web3.eth.getGasPrice();
        const gasPriceEth = web3.utils.fromWei(gasPriceWei, 'ether');
        return gasPriceEth;
    } catch (error) {
        console.error('Error fetching Ethereum gas fee:', error);
        throw new Error('Failed to fetch Ethereum gas fee');
    }
}

module.exports = { getEthereumGas };

require('dotenv').config();
const express = require('express');
const bodyParser = require('body-parser');
const swaggerJsDoc = require('swagger-jsdoc');
const swaggerUi = require('swagger-ui-express');

const { getBitcoinGas } = require('./bitcoinGas.js'); 
const { getDogecoinGas } = require('./dogecoinGas.js'); 
const { getEthereumGas } = require('./ethereumGas.js'); 
const { getSolanaGas } = require('./solanaGas.js'); 
const { getXrpGas } = require('./xrpGas.js'); 

const app = express();
const port = 3000;

const NETWORK = process.env.NETWORK;

app.use(bodyParser.json());

// Swagger configuration
const swaggerOptions = {
    swaggerDefinition: {
        openapi: '3.0.0',
        info: {
            title: 'Crypto Details API',
            version: '1.0.0',
            description: 'API to fetch details of various cryptocurrencies',
            contact: {
                name: 'Sayantan Roy'
            },
            servers: [{ url: `http://localhost:${port}` }]
        },
    },
    apis: [__filename], 
};

const swaggerDocs = swaggerJsDoc(swaggerOptions);
app.use('/api-docs', swaggerUi.serve, swaggerUi.setup(swaggerDocs));

/**
 * @swagger
 * /fetchGasFee:
 *   post:
 *     summary: Fetch the gas fee for a given chain
 *     requestBody:
 *       required: true
 *       content:
 *         application/json:
 *           schema:
 *             type: object
 *             properties:
 *               chain:
 *                 type: string
 *                 example: "ethereum"
 *     responses:
 *       200:
 *         description: Successful response
 *         content:
 *           application/json:
 *             schema:
 *               type: object
 *               properties:
 *                 gasFee:
 *                   type: string
 *                   example: "100 Gwei"
 *       400:
 *         description: Bad request
 *       500:
 *         description: Internal server error
 */
app.post('/fetchGasFee', async (req, res) => {
    const { chain } = req.body;

    if (!chain) {
        return res.status(400).json({ error: 'Chain is required' });
    }

    try {
        const gasFee = await getGasFee(chain);
        res.json({ gasFee });
    } catch (error) {
        console.error('Error:', error.message);
        res.status(500).json({ error: error.message });
    }
});

async function getGasFee(chain) {
    switch (chain.toLowerCase()) {
        case 'bitcoin':
            return getBitcoinGas();
        case 'dogecoin':
            return getDogecoinGas();
        case 'ethereum':
            return getEthereumGas();
        case 'solana':
            return getSolanaGas();
        case 'xrp':
            return getXrpGas();
        default:
            throw new Error('Unsupported chain');
    }
}

app.listen(port, () => {
    console.log(`Server is running on http://localhost:${port}`);
});

node server.js

{
    "chain": "ethereum"
}