Expression expected with const at React JS component

Question

Could you please help me with this?

What I want to do is check if the user is registered. If it is registered it should show the home url and if it is not registered it should show the registration url.

For that I see and check the saved data (isRegistered), if it equals to null is not registered and should show the /register url. But its not working.

In the next line I have an error

const [isReg, setIsReg] = useState(false);

And it gives me this error:

Expression expected.ts(1109)

const App: React.FC = () => (
  
  const [isReg, setIsReg] = useState<boolean>(false);
  
  if(getItem("isRegistered")==null){
    console.log(getItem("isRegistered"));
    useState(true);
  }
  else{
    useState(false);
  }

  <IonApp>
    <IonReactRouter>
    <IonSplitPane contentId="main" when="(min-width: 4096px)">
          <Menu />
      <IonRouterOutlet id="main">

        <Route path="/" render={() => isReg ? {Home} : {Registro}} />
        
        <Route path="/Favorites" component={Favoritos} exact={true}></Route>
     

      </IonRouterOutlet>
      </IonSplitPane>
    </IonReactRouter>
  </IonApp>
);

You need to use setIsReg(true) or false depending the logic and wrap the condition inside a React useEffect hook. — jean182
– jean182, Commented Jan 14, 2021 at 22:28

FireFighter · Accepted Answer · 2021-01-14 22:40:04Z

1

it should be

useEffect(() => {
    if(getItem("isRegistered")==null){
    console.log(getItem("isRegistered"));
    setIsReg(true);
  }
  else{
    setIsReg(false);
  }
}, [])

answered Jan 14, 2021 at 22:40

FireFighter

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6 Comments

JAOdev Over a year ago

thanks but still at const I get: SyntaxError: /home/julian/Documentos/ServicesApp/src/App.tsx: Unexpected token (38:2)

FireFighter Over a year ago

which const do you mean? What line in the code exactly?

JAOdev Over a year ago

the second line: const [isReg, setIsReg] = useState(false);

FireFighter Over a year ago

can you remove the <boolean> part and see if it works? You don't need to define the type, if your initial state is from that type any way.

FireFighter Over a year ago

I know why, you app function is not wrapped in curly braces {}. It is wrapped inside normal brackets (); And wrap the jsx part inside of a return statement.

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