I think I am running into a callback issue as returning the result is saying undefined (despite being shown correctly in the console log).

web3.eth.getBlockNumber(function(error, result){
        return result

I'm unable to pass the callback result to another function/variable currently. Please assist. Thanks.

  • what problem/error are you having? you appear to be returning the result and not passing it anywhere – nyusternie Jan 1 '18 at 1:49
  • try alert(result) to see if it pops up correctly – thefett Jan 1 '18 at 1:51
  • i'm getting undefined in the console and if i alert it. – jack bauer Jan 1 '18 at 1:55
  • have you included web3.js or MetaMask-injected? <script src="https://unpkg.com/web3@1.0.0-beta.27/src/index.js"></script> – nyusternie Jan 2 '18 at 2:06

This is a common point of confusion for new JavaScript developers. If you want to pass result to something else, you need to call another function. E.g.:

web3.eth.getBlockNumber(function (error, result) {

function otherFunction(result) {
  console.log("In otherFunction with: " + result);

Currently, you're just returning result, which just means it gets returned to the caller of your callback, which is web3.eth.getBlockNumber (and it isn't expecting a return value from the callback at all, so it ignores it).

  • ok, but what's the solution? – Dr.X Nov 3 '18 at 17:17
  • I'm not sure what you're asking. My answer includes working code. – user19510 Nov 3 '18 at 17:18

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