Web3.js Batch Request Error – Method.callback is Not a Function in Web3.js Batch Request

batchweb3js

If I try to run the example given here: https://web3js.readthedocs.io/en/1.0/web3-eth.html#batchrequest

With the following code: 

const batch = new web3.BatchRequest();
batch.add(web3.eth.getBalance.request('0x0000000000000000000000000000000000000000', 'latest'));

batch.execute()
.then(res => console.log(res))
.catch(err => console.log(err));

I get the error: 

TypeError: method.callback is not a function

Does anybody have experience with this?

version:
"web3": "^1.0.0-beta.55"

Best Answer

For some reason (this is not documented anywhere I could find) the request method requires a callback function as a last parameter, as such:

const batch = new web3.BatchRequest();
batch.add(web3.eth.getBalance.request('0x0000000000000000000000000000000000000000', 'latest', (err, res) => console.log(err, res));

batch.execute()
.then(res => console.log(res))
.catch(err => console.log(err));
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