e-book

web3-provider.effects.ts

 metaMaskEnabled$ = createEffect(() =>
    this.actions$.pipe(
      ofType(ROOT_EFFECTS_INIT),
      map(() => {
       
        const ethereum = (window as any).ethereum;
        // Returns true or false, representing whether the user has MetaMask installed.
        if (!ethereum || !ethereum.isMetaMask) {
          return ErrorActions.errorMessage({ errorMsg: `Please install MetaMask.` });
        }
        return Web3ProviderActions.emptyAction();
      })
    )
  );