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.


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

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

        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

  • Are these documented anywhere? – Daniel Que Jul 27 '18 at 20:21
  • 1
    For web3 >1.0.0 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

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

  method: "eth_getBalance",
  params: ['0x407d73d8a49eeb85d32cf465507dd71d507100c1', 'latest'],
  jsonrpc: "2.0",
  id: new Date().getTime()
} function (error, result) {...})
  • +1 for dynamic id generation for avoiding collisions. – Daniel Kmak Jul 22 '18 at 12:14

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