ethereum stack exchange question

web3_setup

if (typeof window !== "undefined" && typeof window.web3 !== "undefined") {
  // In the browser and metamask is running
  web3 = new Web3(window.web3.currentProvider);
} else {
  // We are on the server *OR* the user is not running metamask
  const provider = new Web3.providers.HttpProvider(
    "https://rinkeby.infura.io/v3/bb20540179824ccb94cf748904d43090"
  );
  web3 = new Web3(provider);
}