Error: invalid type (arg="type", value="a") web3.js

Question

I am trying to get the balance of user for specific token type using web3.js.

Here is my code block:

    var tokenContract = new web3.eth.Contract(erc20abi, tokenAddress)
    tokenContract.methods.balanceOf(accounts[0]).call().then(balance => {
              console.log(balance);
    });

It throws an error as soon as this function is called from web3.

Following is the error at my console:

Uncaught (in promise) Error: invalid type (arg="type", value="a")

at Object.n [as throwError] (web3.min.js:1)
at D (web3.min.js:1)
at web3.min.js:1
at Array.forEach (<anonymous>)
at web3.min.js:1
at D (web3.min.js:1)
at e.<anonymous> (web3.min.js:1)
at Array.forEach (<anonymous>)
at e.encode (web3.min.js:1)
at a.encodeParameters (web3.min.js:1)**

My web3.js version is: 1.2.7

Here are values from the variables used:

1. accounts[0] = "0x572ACD5370909b2C0aCde66995c1BE8aC25238bE"

2. tokenAddress = "0xfd60bC45f816b575C2c938F744CFb801505824E7"

3. erc20abi = [{ "constant": true, "inputs": [], "name": "name", "outputs": [{ "name": "", "type": "string" }], "payable": false, "type": "function" }, { "constant": true, "inputs": [], "name": "decimals", "outputs": [{ "name": "", "type": "uint8" }], "payable": false, "type": "function" }, { "constant": true, "inputs": [{ "type": "address" }], "name": "balanceOf", "outputs": [{ "type": "uint256" }], "payable": false, "type": "function" }, { "constant": true, "inputs": [], "name": "symbol", "outputs": [{ "name": "", "type": "string" }], "payable": false, "type": "function" }, { "constant": true, "inputs": [{ "internalType": "address", "type": "address" }], "name": "balanceOf", "outputs": [{ "internalType": "uint256", "type": "uint256" }], "payable": false, "stateMutability": "view", "type": "function" } ];

Answer 1

Looks like you're using an older ABI format (or at least an unconventional one).

Change this:

"internalType":"address"

And this:

"internalType":"uint256"

To this:

"name":""

---

UPDATE:

It also seems that you have two balanceOf functions in your ABI, god knows why (maybe an attempt to support both formats). So to generalize the answer above, just use this one:

{
    "constant"        : true,
    "inputs"          : [{"name":"","type":"address"}],
    "name"            : "balanceOf",
    "outputs"         : [{"name":"","type":"uint256"}],
    "payable"         : false,
    "stateMutability" : "view",
    "type"            : "function"
}

It should be one of the elements in the erc20abi array of course.