I am trying to get abi of a token with etherscan and pass the variable in to the web3 function. I am using etherscan's getabi built in function as it is shown in the API documentation but I am still getting an error.


const express = require('express')
const bodyParser = require('body-parser')
const http = require('http')
const Web3 = require('web3')
const HDWalletProvider = require('@truffle/hdwallet-provider')
const moment = require('moment-timezone')
const numeral = require('numeral')
const ethapi = require('etherscan-api').init(process.env.ETHAPI)
const _ = require('lodash')
const axios = require('axios')

const PORT = process.env.PORT || 5000
const app = express();
const server = http.createServer(app).listen(PORT, () => console.log(`Listening on ${ PORT }`))

const web3 = new Web3(process.env.RPC_URL)


// Uniswap Factory Contract: https://etherscan.io/address/0xc0a47dfe034b400b47bdad5fecda2621de6c4d95#code
const UNISWAP_FACTORY_ABI = [{"name":"NewExchange","inputs":[{"type":"address","name":"token","indexed":true},{"type":"address","name":"exchange","indexed":true}],"anonymous":false,"type":"event"},{"name":"initializeFactory","outputs":[],"inputs":[{"type":"address","name":"template"}],"constant":false,"payable":false,"type":"function","gas":35725},{"name":"createExchange","outputs":[{"type":"address","name":"out"}],"inputs":[{"type":"address","name":"token"}],"constant":false,"payable":false,"type":"function","gas":187911},{"name":"getExchange","outputs":[{"type":"address","name":"out"}],"inputs":[{"type":"address","name":"token"}],"constant":true,"payable":false,"type":"function","gas":715},{"name":"getToken","outputs":[{"type":"address","name":"out"}],"inputs":[{"type":"address","name":"exchange"}],"constant":true,"payable":false,"type":"function","gas":745},{"name":"getTokenWithId","outputs":[{"type":"address","name":"out"}],"inputs":[{"type":"uint256","name":"token_id"}],"constant":true,"payable":false,"type":"function","gas":736},{"name":"exchangeTemplate","outputs":[{"type":"address","name":"out"}],"inputs":[],"constant":true,"payable":false,"type":"function","gas":633},{"name":"tokenCount","outputs":[{"type":"uint256","name":"out"}],"inputs":[],"constant":true,"payable":false,"type":"function","gas":663}]
const UNISWAP_FACTORY_ADDRESS = '0xc0a47dfe034b400b47bdad5fecda2621de6c4d95'
const uniswapFactoryContract = new web3.eth.Contract(UNISWAP_FACTORY_ABI, UNISWAP_FACTORY_ADDRESS)

// Uniswap Exchange Template: https://etherscan.io/address/0x09cabec1ead1c0ba254b09efb3ee13841712be14#code
const UNISWAP_EXCHANGE_ABI = [{"name": "TokenPurchase", "inputs": [{"type": "address", "name": "buyer", "indexed": true}, {"type": "uint256", "name": "eth_sold", "indexed": true}, {"type": "uint256", "name": "tokens_bought", "indexed": true}], "anonymous": false, "type": "event"}, {"name": "EthPurchase", "inputs": [{"type": "address", "name": "buyer", "indexed": true}, {"type": "uint256", "name": "tokens_sold", "indexed": true}, {"type": "uint256", "name": "eth_bought", "indexed": true}], "anonymous": false, "type": "event"}, {"name": "AddLiquidity", "inputs": [{"type": "address", "name": "provider", "indexed": true}, {"type": "uint256", "name": "eth_amount", "indexed": true}, {"type": "uint256", "name": "token_amount", "indexed": true}], "anonymous": false, "type": "event"}, {"name": "RemoveLiquidity", "inputs": [{"type": "address", "name": "provider", "indexed": true}, {"type": "uint256", "name": "eth_amount", "indexed": true}, {"type": "uint256", "name": "token_amount", "indexed": true}], "anonymous": false, "type": "event"}, {"name": "Transfer", "inputs": [{"type": "address", "name": "_from", "indexed": true}, {"type": "address", "name": "_to", "indexed": true}, {"type": "uint256", "name": "_value", "indexed": false}], "anonymous": false, "type": "event"}, {"name": "Approval", "inputs": [{"type": "address", "name": "_owner", "indexed": true}, {"type": "address", "name": "_spender", "indexed": true}, {"type": "uint256", "name": "_value", "indexed": false}], "anonymous": false, "type": "event"}, {"name": "setup", "outputs": [], "inputs": [{"type": "address", "name": "token_addr"}], "constant": false, "payable": false, "type": "function", "gas": 175875}, {"name": "addLiquidity", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "min_liquidity"}, {"type": "uint256", "name": "max_tokens"}, {"type": "uint256", "name": "deadline"}], "constant": false, "payable": true, "type": "function", "gas": 82616}, {"name": "removeLiquidity", "outputs": [{"type": "uint256", "name": "out"}, {"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "amount"}, {"type": "uint256", "name": "min_eth"}, {"type": "uint256", "name": "min_tokens"}, {"type": "uint256", "name": "deadline"}], "constant": false, "payable": false, "type": "function", "gas": 116814}, {"name": "__default__", "outputs": [], "inputs": [], "constant": false, "payable": true, "type": "function"}, {"name": "ethToTokenSwapInput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "min_tokens"}, {"type": "uint256", "name": "deadline"}], "constant": false, "payable": true, "type": "function", "gas": 12757}, {"name": "ethToTokenTransferInput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "min_tokens"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "recipient"}], "constant": false, "payable": true, "type": "function", "gas": 12965}, {"name": "ethToTokenSwapOutput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_bought"}, {"type": "uint256", "name": "deadline"}], "constant": false, "payable": true, "type": "function", "gas": 50463}, {"name": "ethToTokenTransferOutput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_bought"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "recipient"}], "constant": false, "payable": true, "type": "function", "gas": 50671}, {"name": "tokenToEthSwapInput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_sold"}, {"type": "uint256", "name": "min_eth"}, {"type": "uint256", "name": "deadline"}], "constant": false, "payable": false, "type": "function", "gas": 47503}, {"name": "tokenToEthTransferInput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_sold"}, {"type": "uint256", "name": "min_eth"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "recipient"}], "constant": false, "payable": false, "type": "function", "gas": 47712}, {"name": "tokenToEthSwapOutput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "eth_bought"}, {"type": "uint256", "name": "max_tokens"}, {"type": "uint256", "name": "deadline"}], "constant": false, "payable": false, "type": "function", "gas": 50175}, {"name": "tokenToEthTransferOutput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "eth_bought"}, {"type": "uint256", "name": "max_tokens"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "recipient"}], "constant": false, "payable": false, "type": "function", "gas": 50384}, {"name": "tokenToTokenSwapInput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_sold"}, {"type": "uint256", "name": "min_tokens_bought"}, {"type": "uint256", "name": "min_eth_bought"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "token_addr"}], "constant": false, "payable": false, "type": "function", "gas": 51007}, {"name": "tokenToTokenTransferInput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_sold"}, {"type": "uint256", "name": "min_tokens_bought"}, {"type": "uint256", "name": "min_eth_bought"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "recipient"}, {"type": "address", "name": "token_addr"}], "constant": false, "payable": false, "type": "function", "gas": 51098}, {"name": "tokenToTokenSwapOutput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_bought"}, {"type": "uint256", "name": "max_tokens_sold"}, {"type": "uint256", "name": "max_eth_sold"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "token_addr"}], "constant": false, "payable": false, "type": "function", "gas": 54928}, {"name": "tokenToTokenTransferOutput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_bought"}, {"type": "uint256", "name": "max_tokens_sold"}, {"type": "uint256", "name": "max_eth_sold"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "recipient"}, {"type": "address", "name": "token_addr"}], "constant": false, "payable": false, "type": "function", "gas": 55019}, {"name": "tokenToExchangeSwapInput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_sold"}, {"type": "uint256", "name": "min_tokens_bought"}, {"type": "uint256", "name": "min_eth_bought"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "exchange_addr"}], "constant": false, "payable": false, "type": "function", "gas": 49342}, {"name": "tokenToExchangeTransferInput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_sold"}, {"type": "uint256", "name": "min_tokens_bought"}, {"type": "uint256", "name": "min_eth_bought"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "recipient"}, {"type": "address", "name": "exchange_addr"}], "constant": false, "payable": false, "type": "function", "gas": 49532}, {"name": "tokenToExchangeSwapOutput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_bought"}, {"type": "uint256", "name": "max_tokens_sold"}, {"type": "uint256", "name": "max_eth_sold"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "exchange_addr"}], "constant": false, "payable": false, "type": "function", "gas": 53233}, {"name": "tokenToExchangeTransferOutput", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_bought"}, {"type": "uint256", "name": "max_tokens_sold"}, {"type": "uint256", "name": "max_eth_sold"}, {"type": "uint256", "name": "deadline"}, {"type": "address", "name": "recipient"}, {"type": "address", "name": "exchange_addr"}], "constant": false, "payable": false, "type": "function", "gas": 53423}, {"name": "getEthToTokenInputPrice", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "eth_sold"}], "constant": true, "payable": false, "type": "function", "gas": 5542}, {"name": "getEthToTokenOutputPrice", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_bought"}], "constant": true, "payable": false, "type": "function", "gas": 6872}, {"name": "getTokenToEthInputPrice", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "tokens_sold"}], "constant": true, "payable": false, "type": "function", "gas": 5637}, {"name": "getTokenToEthOutputPrice", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "uint256", "name": "eth_bought"}], "constant": true, "payable": false, "type": "function", "gas": 6897}, {"name": "tokenAddress", "outputs": [{"type": "address", "name": "out"}], "inputs": [], "constant": true, "payable": false, "type": "function", "gas": 1413}, {"name": "factoryAddress", "outputs": [{"type": "address", "name": "out"}], "inputs": [], "constant": true, "payable": false, "type": "function", "gas": 1443}, {"name": "balanceOf", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "address", "name": "_owner"}], "constant": true, "payable": false, "type": "function", "gas": 1645}, {"name": "transfer", "outputs": [{"type": "bool", "name": "out"}], "inputs": [{"type": "address", "name": "_to"}, {"type": "uint256", "name": "_value"}], "constant": false, "payable": false, "type": "function", "gas": 75034}, {"name": "transferFrom", "outputs": [{"type": "bool", "name": "out"}], "inputs": [{"type": "address", "name": "_from"}, {"type": "address", "name": "_to"}, {"type": "uint256", "name": "_value"}], "constant": false, "payable": false, "type": "function", "gas": 110907}, {"name": "approve", "outputs": [{"type": "bool", "name": "out"}], "inputs": [{"type": "address", "name": "_spender"}, {"type": "uint256", "name": "_value"}], "constant": false, "payable": false, "type": "function", "gas": 38769}, {"name": "allowance", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [{"type": "address", "name": "_owner"}, {"type": "address", "name": "_spender"}], "constant": true, "payable": false, "type": "function", "gas": 1925}, {"name": "name", "outputs": [{"type": "bytes32", "name": "out"}], "inputs": [], "constant": true, "payable": false, "type": "function", "gas": 1623}, {"name": "symbol", "outputs": [{"type": "bytes32", "name": "out"}], "inputs": [], "constant": true, "payable": false, "type": "function", "gas": 1653}, {"name": "decimals", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [], "constant": true, "payable": false, "type": "function", "gas": 1683}, {"name": "totalSupply", "outputs": [{"type": "uint256", "name": "out"}], "inputs": [], "constant": true, "payable": false, "type": "function", "gas": 1713}]

//Token ABI

async function getContractFromAddress(contractAddress) {
    let contractABI = (await ethapi.contract.getabi(contractAddress)).result
    let tokenContract = new web3.eth.Contract(contractABI,contractAddress)
    return tokenContract
var contractAddress='0xbcf9dbf8b14ed096b2ba08b7269356197fdd1b5d'
//  var contractABI= await ethapi.contract.getabi(contractAddress);
// var tokenContract = new web3.eth.Contract(contractABI,contractAddress);
// var contractABI=JSON.stringify(ethapi.contract.getabi(contractAddress))

async function checkPair(args) {
  const { inputTokenSymbol, inputTokenAddress, outputTokenSymbol, outputTokenAddress, inputAmount } = args

  const exchangeAddress = await uniswapFactoryContract.methods.getExchange(outputTokenAddress).call()
  const exchangeContract = new web3.eth.Contract(UNISWAP_EXCHANGE_ABI, exchangeAddress)

  const uniswapResult = await exchangeContract.methods.getEthToTokenInputPrice(inputAmount).call()
    'Input Token': inputTokenSymbol,
    'Output Token': outputTokenSymbol,
    'Input Amount': web3.utils.fromWei(inputAmount, 'Ether'),
    'Uniswap Return': web3.utils.fromWei(uniswapResult, 'Ether'),
    'Timestamp': moment().tz('Turkey/Istanbul').format(),

let priceMonitor
let monitoringPrice = false

async function monitorPrice() {
  if(monitoringPrice) {

  console.log("Checking prices...")
  monitoringPrice = true

  try {

    let tokenContract = await getContractFromAddress(contractAddress)

     await checkPair({
       inputTokenSymbol: 'ETH',
       inputTokenAddress: '0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee',
       outputTokenSymbol: await tokenContract.methods.symbol().call(),
       outputTokenAddress: contractAddress,
       inputAmount: web3.utils.toWei('1', 'ETHER')


  } catch (error) {
    monitoringPrice = false

  monitoringPrice = false

// Check markets every n seconds
const POLLING_INTERVAL = process.env.POLLING_INTERVAL || 3000 // 3 Seconds
priceMonitor = setInterval(async () => { await monitorPrice() }, POLLING_INTERVAL)

and this is the error I am getting:

> node index.js

        return new Error('You must provide the json interface of the contract when instantiating a contract object.');
Error: You must provide the json interface of the contract when instantiating a contract object.
    at Object.ContractMissingABIError (/Users/Kantemirovs/price-bot/node_modules/web3-core-helpers/lib/errors.js:107:16)
    at Contract (/Users/Kantemirovs/price-bot/node_modules/web3-eth-contract/lib/index.js:61:22)
    at new Contract (/Users/Kantemirovs/price-bot/node_modules/web3-eth/lib/index.js:257:22)
    at Object.<anonymous> (/Users/Kantemirovs/price-bot/index.js:40:21)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
    at Module.load (internal/modules/cjs/loader.js:928:32)
    at Function.Module._load (internal/modules/cjs/loader.js:769:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
    at internal/main/run_main_module.js:17:47
npm ERR! errno 1
npm ERR! trading-bot@0.3.0 start: `node index.js`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the trading-bot@0.3.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/Kantemirovs/.npm/_logs/2021-01-20T15_40_34_485Z-debug.log

THIS IS THE API DOCUMENTATIO FOR ETHERSCAN : https://sebs.github.io/etherscan-api/#etherscanapi

Can somebody please help me with this issue?

  • This question was closed for focus because typically you need to be more specific and do a bit more debugging rather than pasting a whole bunch of code and asking for an answer. You were lucky here :)
    – eth
    Jan 29, 2021 at 2:06

1 Answer 1


ethapi.contract.getabi() returns a promise, not the ABI. You can take advantage of async await in order to wait for the promise response.

async function getContractFromAddress(contractAddress) {
    let contractABI = (await ethapi.contract.getabi(contractAddress)).result
    let tokenContract = new web3.eth.Contract(contractABI,contractAddress)
    return tokenContract

Then you can replace your original

var contractABI=ethapi.contract.getabi(contractAddress);
var tokenContract = new web3.eth.Contract(contractABI,contractAddress);


let tokenContract = await getContractFromAddress(contractAddress)
  • If this answers your question, please consider accepting the answer, thanks! Jan 20, 2021 at 16:38
  • Hi, I tried this method. I am getting the following error: let tokenContract = await getContractFromAddress('0xbcf9dbf8b14ed096b2ba08b7269356197fdd1b5d') ^^^^^ SyntaxError: await is only valid in async function
    – Itsjonie
    Jan 20, 2021 at 16:54
  • You have to use the getContractFromAddress function into an async function. Either you implement this line in the monitorPrice function that you are using, considering you call tokenContract only there and that the function is async. Alternatively, as you are dealing with a lot of promises (price fetching, contract fetching, contract execution ...) You could make a global execution function: const init = async () => { <all your async await code> } and then you simply call it by doing init(). Jan 20, 2021 at 17:01
  • Pro tip which is unrelated: checking prices of few pairs in this way may work, but if your intentions are to loop through all pairs and call the checkPair function for each pair every x seconds, it won't be efficient enough. It will be slow, and probably you would hit infura's call limit fast. If you need guidance for the appropriate and efficient way to do it, let me know. Jan 20, 2021 at 17:08
  • I just want to check the price of one contract every 3 seconds. Also, I am going to sound a little dumb here but can you show me how to implement getContractFromAddress function into monitor price.
    – Itsjonie
    Jan 20, 2021 at 17:15

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