How to trigger change blockchain network request on MetaMask

Question

I am using web3 for my first app test and I'd like to make it so MetaMask will prompt the user to change the network to Binance (BSC) network if it is not selected already, just like here:

How to trigger such a request?

Answer 1

was finally able to find the answer:

await window.ethereum.request({ method: 'wallet_switchEthereumChain', params: [{ chainId: '0x61' }], // chainId must be in hexadecimal numbers });
A more comprehensive answer would check if MetaMask is installed and if this one has installed the chain your Dapp wants to connect to, and if it is not install it:

// Check if MetaMask is installed // MetaMask injects the global API into window.ethereum if (window.ethereum) { try { // check if the chain to connect to is installed await window.ethereum.request({ method: 'wallet_switchEthereumChain', params: [{ chainId: '0x61' }], // chainId must be in hexadecimal numbers }); } catch (error) { // This error code indicates that the chain has not been added to MetaMask // if it is not, then install it into the user MetaMask if (error.code === 4902) { try { await window.ethereum.request({ method: 'wallet_addEthereumChain', params: [ { chainId: '0x61', rpcUrl: 'https://data-seed-prebsc-1-s1.binance.org:8545/', }, ], }); } catch (addError) { console.error(addError); } } console.error(error); } } else { // if no window.ethereum then MetaMask is not installed alert('MetaMask is not installed. Please consider installing it: https://metamask.io/download.html'); }