I am new to Etherium smart contracts. I have created a smart contract and deployed it on https://kovan.etherscan.io. Now I am trying to access this contract from node js. below is my code but I am not getting how to set provider and further things. Can anybody help me with this?

const Web3 = require('web3');
const web3 = new Web3(Web3.givenProvider || 'ws://localhost:8546', null, {});

module.exports = {
        tmp1: function (req, res, next){
function Image (req,res){ 
        const abi =[{ my json of abi}];
        var contractInstance = web3.eth.contract(abi).at('0xB02542CF6C19B70813694EB9CFD60C10a796d83f');
        var result = contractInstance.buyCoordinator(req.query.coordinator,req.query.coimage).call();

I am totally confused about how to set provider https://kovan.etherscan.io and how exactly it will work or know that I have deployed contract here and my account address.

  • result returns promise, so you have to async/await it or use .then()
    – rstormsf
    Commented Apr 27, 2019 at 8:44

1 Answer 1


The reason your method won't work is because you aren't connecting to Kovan testnet anywhere. Go to http://infura.io and create a Kovan testnet account (if you don't have one already). Infura provides you with an "API KEY" for kovan.

import Web3 from 'web3' //or const Web3 = require('web3'); or direct import from node_modules

const testnet = `https://kovan.infura.io/'+API_KEY
const web3 = new Web3( new Web3.providers.HttpProvider(testnet) )

Another way of doing it is in conjunction with Truffle and Infura: On creating an infura kovan testnet account, you also get the 12 words for mnemonic.

const Web3 = require(‘web3’);
const MNEMONIC = <YOUR 12 words e.g.: ‘aquaman superman batman shazam flash wonderwoman greenlantern ironman captainamerica hulk blackwidow thanos’>
const API_KEY = ..

const provider = new HDWalletProvider(MNEMONIC, ‘https://kovan.infura.io/'+API_KEY);
const web3 = new Web3(provider);
  • I create a new API key. Now it seems the provider is set properly. Thanx!!
    – Varsh
    Commented May 2, 2019 at 6:32
  • Great thanks! Please upvote the answer and mark it as the solution! Commented May 2, 2019 at 9:43

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