This is a simple contract I am trying out with an Ethereum testrpc instance.

pragma solidity ^0.4.11;
/// @title List

// Begin contract defintion
contract List {

    struct ListMembers {
        bytes32 listOwner;
        bytes32[] members;
        uint256 rNumber;
        uint256 aNumber; 
        uint256 uNumber;  

    ListMembers public lm;
    mapping (bytes32 => bool) public addedMembers;

    function List(bytes32 listOwner) {
        lm.listOwner = listOwner;
        lm.rNumber = 10000;
        lm.aNumber = 0;
        lm.uNumber = 0;

And, this is the web3.js code to deploy the contract.

var Web3 = require('web3');
var fs = require('fs');
var ethHttpProvider = new Web3.providers.HttpProvider("http://localhost:8545");
var web3 = new Web3(ethHttpProvider);
var abiFile = fs.readFileSync('Lists.abi').toString();
var abiDef = JSON.parse(abiFile);
var byteCode = fs.readFileSync('Lists.bin').toString();
var listContract = web3.eth.contract(abiDef);
deployedContract = listContract.new('A',{data: byteCode, from: web3.eth.accounts[0], gas: 4700000});

And, this is the error I am getting:

TypeError: value.forEach is not a function

What am I missing?

  • i think the error comes from the provided constructor parameter 'A'
    – Badr Bellaj
    Commented Aug 25, 2017 at 20:06
  • Also data should have a '0x' in front. Something like {data: '0x' + byteCode ...}.
    – Ismael
    Commented Aug 26, 2017 at 1:33
  • Yes. What is the correct way of passing argument? Commented Aug 26, 2017 at 2:09
  • The correct format is to pass it as an array element as described here. So, it is, listContract.new(['A'],...) github.com/ethereum/wiki/wiki/JavaScript-API#web3ethcontract Commented Aug 26, 2017 at 4:51

1 Answer 1


The correct format is to pass it as an array element as described in wiki. So, it is, listContract.new(['A'],...)

  • web3.js should be validating its input types... so this should be submitted as an issue on their github page.
    – Paul S
    Commented Apr 7, 2018 at 18:23
  • I had a similar error with passing the abi the wrong way. It helped to pass the object with a JSON.parse after require() the file. Like this JSON.parse(combinedJson.contracts.contractName.abi)
    – sunwarr10r
    Commented Feb 12, 2019 at 17:14

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