Get chainId from user

Im using vanilla js (no react components), and just metamask (no walletconnect). How do I get the chainId of the network the user is currently logged in to? I have another web3 connection to a speedynode pulling some mainnet info, but while I’m developing, I’d like to do things like make sure the user is on the Polygon Mainnet before they interact with any contracts

await Moralis.enableWeb3()
chainId = await Moralis.getChainId()