I'm currently struggling to interact with my smart contract, I don't if it comes from the way I call the function or the way I connect to my smart contract. Here is the code

const contractAddress = '0xf85fe12e1eb30844422e95252b68bb1fbbbe7fc6';

const Web3 = require('web3');

window.addEventListener('load', async function () {
    if (typeof web3 !== 'undefined') {
        console.log('Web3 Detected! ' + web3.currentProvider.constructor.name)
        window.web3 = new Web3(web3.currentProvider);

        await ethereum.enable();
        console.log('address: ' + web3.eth.accounts[0])

        web3.eth.getBalance(web3.eth.accounts[0], (err, wei) => {

          console.log('le balance est ' + web3.fromWei(wei, 'ether'))

        var contract = new web3.eth.contract(ABI).at(contractAddress);//, contractAddress);
        console.log(await contract.isOpen.call());
        // console.log(await contract.methods.isOpen.call());
        //console.log(await contract.methods.isOpen());

    else {
        document.getElementById('output').innerHtml = 'Please download and install Metamask: <a href="https://metamask.io/">https://metamask.io/</a>'

here, the error in the browser

index.js:482 Uncaught (in promise) TypeError: Cannot read property 'isOpen' of undefined

at index.js:482

I have no problem with it on server side with nodejs and infura, but on client side using metamask, web3 functions looks like different, no?

Thanks for you helps

  • 1
    Assuming that you're using web3.js v1.x, change new web3.eth.contract to new web3.eth.Contract. Commented Apr 24, 2019 at 5:44
  • I installed the 1.x with node js, if I look at in the browser's console with console,log(web3), it says that I'm using the version 0.20.4. However, I install the 6.3.2 metamask version, which is the last I guess. What's wrong? How can I update this version to 1.0?
    – champi
    Commented Apr 24, 2019 at 6:12
  • Obviously, if I try with new web3.eth.Contract it tells me the constuctor doesn't exist.
    – champi
    Commented Apr 24, 2019 at 6:13
  • With web3.js v0.x, just remove the new. Commented Apr 24, 2019 at 6:52
  • And of course, I'm not sure what your ABI is, but it should be an array of objects (not a string, in case you have it this way). Commented Apr 24, 2019 at 6:54

1 Answer 1


using version 0.20.x with metamask.

it worked by doing

//create a contract instance
contract = window.web3.eth.contract(ABI).at(contractAddress);
//call function isOpen() in the contract
contract.isOpen((err,res) =>{ console.log(res)});

Thanks for the help!

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