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Is it possible to figure out whether the network is mainnet or testnet (Ropsten) from web3.js? Or through MetaMask?

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1
  • Use ES6: await web3.eth.net.getNetworkType((err, network)=> {...}); – Russo Oct 1 '18 at 14:12
41

Prior to Web 1.0 you can use web3.version.getNetwork as following: 

web3.version.getNetwork((err, netId) => {
  switch (netId) {
    case "1":
      console.log('This is mainnet')
      break
    case "2":
      console.log('This is the deprecated Morden test network.')
      break
    case "3":
      console.log('This is the ropsten test network.')
      break
    default:
      console.log('This is an unknown network.')
  }
})

WEB 1.0 :

Since web 1.0 we have web3.eth.net.getNetworkType which Guesses the network we are connected to.

web3.eth.net.getNetworkType()
.then(console.log);

It returns a string referring network's name :

  • "main" for main network
  • "morden" for the morden test network
  • "ropsten" for the ropsten test network
  • "private" for undetectable networks.
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  • Use ES6: await web3.eth.net.getNetworkType((err, network)=> {...}); – Russo Oct 1 '18 at 14:11
9

web3.version.network or the async version web3.version.getNetwork() allow one to directly determine the network ID from web3.js.

Usage is as expected:

var network = web3.version.network

Network IDs can be found in this thread.

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3
  • This might lead to exceptions stating that it is no good to access web3 methods synchronously. I had it this way and ran into issues in my rendering of react components, so i changed it to the accepted answer – David Fariña Mar 6 '18 at 17:56
  • 1
    web3.version.getNetwork() is asynchronous, for what it's worth. – Matthew Schmidt Mar 7 '18 at 23:21
  • youre right of course, but the only code fragment you actually formatted as code is the synchronous version which should be avoided, especially since there is a async variant. Didnt want to make your post down or anything, just wanted to give a helpful sidenote on that topic – David Fariña Mar 8 '18 at 11:25
8

For web3 1.0.0 you should do:

web3.eth.net.getId().then(netId => {
  switch (netId) {
    case 1:
      console.log('This is mainnet')
      break
    case 2:
      console.log('This is the deprecated Morden test network.')
      break
    case 3:
      console.log('This is the ropsten test network.')
      break
    default:
      console.log('This is an unknown network.')
  }
})
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7

In addition to @Badr's answer, there are two more test networks, Rinkeby and Kovan:

switch (networkId) {
  case "1":
    networkName = "Main";
    break;
  case "2":
   networkName = "Morden";
   break;
  case "3":
    networkName = "Ropsten";
    break;
  case "4":
    networkName = "Rinkeby";
    break;
  case "42":
    networkName = "Kovan";
    break;
  default:
    networkName = "Unknown";
}

UPDATE: web3@1.0.0 has a web3.eth.net.getNetworkType([callback]) function to get a network name guess

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0

Is it possible to figure out whether the network is mainnet or testnet (Ropsten) from web3.js?

This has been asked before, and is answered here: Getting Go-Ethereum current network id

In addition to these suggestions, you could take a look a the net_version RPC call.

Or through MetaMask?

The main MetaMask pop-up shows the network you're connected to in the top left. It also functions as a drop-down, to allow you to select which network you want it to connect to.

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