Call an arbitrary JSON-RPC method with web3

Question

I want to use web3 to call evm_snapshot (only available on testrpc). This is not in web3's list of methods, but I don't want to have to make an actual http call.

score 11 · Accepted Answer · answered May 13 '16 at 03:07

11

In addition to sendAsync, you can extend web3 like so:

    web3._extend({
        property: 'evm',
        methods: [new web3._extend.Method({
            name: 'snapshot',
            call: 'evm_snapshot',
            params: 0,
            outputFormatter: toIntVal
        })]
    });

    web3._extend({
        property: 'evm',
        methods: [new web3._extend.Method({
            name: 'revert',
            call: 'evm_revert',
            params: 1,
            inputFormatter: [toIntVal]
        })]
    });

That way you can use the command just like any other method, so it's far more readable.

Also, if you don't want to deal with implementing these methods yourself, you can use my extended web3

answered May 13 '16 at 03:07

Tjaden Hess

37,046
10
91
118

Are these documented anywhere? – Daniel Que Jul 27 '18 at 20:21
1

For web3 >1.0.0 https://web3js.readthedocs.io/en/1.0/web3.html#extend. I don't know if there's docs for web3 <1.0.0, which is what this answer is based on – Tjaden Hess Jul 27 '18 at 21:46
Thanks for the fast reply! Yeah I couldn't find it in 0.20.x. Also can't find sendAsync docs. – Daniel Que Jul 27 '18 at 21:52

score 8 · Answer 2 · answered May 12 '16 at 23:43

8

Looks like I can use web3.currentProvider.sendAsync().

web3.currentProvider.sendAsync({
  method: "eth_getBalance",
  params: ['0x407d73d8a49eeb85d32cf465507dd71d507100c1', 'latest'],
  jsonrpc: "2.0",
  id: new Date().getTime()
} function (error, result) {...})

answered May 12 '16 at 23:43

Jehan

783
1
7
11

+1 for dynamic id generation for avoiding collisions. – Daniel Jul 22 '18 at 12:14

score 0 · Answer 3 · answered Nov 03 '21 at 13:46

Improving a bit Jehan's answer:

  window.ethereum.sendAsync({
  method: "eth_getBalance",
  params: ['0x407d73d8a49eeb85d32cf465507dd71d507100c1', 'latest'],
  jsonrpc: "2.0",
  id: new Date().getTime()
} , function (error, result){
           console.log(result);
       });

Call an arbitrary JSON-RPC method with web3

3 Answers3

Linked