How to connect to the Ropsten test-net using web3.js

Question

I want to connect to the Ropsten test-net:

    // Is there is an injected web3 instance?
    if (typeof web3 !== 'undefined') {
      App.web3Provider = web3.currentProvider;
      web3 = new Web3(web3.currentProvider);
    } else {
      // If no injected web3 instance is detected, fallback to the TestRPC.
      App.web3Provider = new web3.providers.HttpProvider('http://localhost:8545');
      web3 = new Web3(App.web3Provider);
    }

I have http://localhost:8545 in this code. How do I connect to Ropsten instead of http://localhost:8545?

score 14 · Accepted Answer · edited Apr 09 '19 at 17:50

14

You can either run a local node and specify your chain using --chain ropsten when starting geth/parity and connect to localhost once sync is completed or you can connect to infura.io:

var web3 = new Web3(new Web3.providers.HttpProvider(
    'https://ropsten.infura.io/v3/[infura_project_id]'
));

edited Apr 09 '19 at 17:50

AVK

5
3

answered Sep 27 '17 at 15:19

d9ngle

436
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10

geth --testnet --chain ropsten --rpc Got this error: Incorrect Usage. flag provided but not defined: -chain – Muhammad Shahzad Apr 18 '18 at 17:01
1

@MuhammadShahzad try omitting --testnet – d9ngle Apr 18 '18 at 19:00
web3.eth.personal.currentProvider.connected = false for me. Tried Infura ropsten, kovan and local ganache. – Philip Rego Sep 07 '20 at 00:18

information_interchange · Answer 2 · 2018-05-26T15:26:48.930

3

You can also install metamask, which will inject web3 into the javascript runtime environment (assuming you are running this in the browser). From metamask, you can then select the chain/network as shown:

edited May 26 '18 at 15:26

answered May 26 '18 at 15:21

information_interchange

139
4

For using this approach wee should run webpage on local server. – Stepan Poperechnyi May 30 '19 at 08:49

score 0 · Answer 3 · edited Aug 06 '21 at 04:36

0

To get infura links, please use : https://infura.io/

edited Aug 06 '21 at 04:36

Ismael

30,570
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answered May 03 '18 at 12:18

Stepan Poperechnyi

790
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How to connect to the Ropsten test-net using web3.js

3 Answers3