TSX 解析错误：箭头 function 上预期的表达式

Question

How can i solve this error? TS1109: Expression expected. I'm new to typescript and I don't understand why is error popping up. Any suggestions please?

  const checkIfUserIsLoggedIn = () : boolean => {
    return if (localStorage.getItem("logged-in") === "true" ) {
      return <LoggedInMp/>
    } else {
      return <NotLoggedInMp/>
    }
  }

Answer 1

You have a few errors in your code. The return in front of the if is wrong and the return type of your function may also be off. The first return is causing the error, because an expression is expected and a if {} else {} is not an expression.

const checkIfUserIsLoggedIn = () => {
    if (localStorage.getItem("logged-in") === "true" ) {
      return <LoggedInMp/>;
    } else {
      return <NotLoggedInMp/>;
    }
}

Answer 2

Additional to the accepted answer, you could even make this an one-liner:

const checkIfUserIsLoggedIn = () => localStorage.getItem("logged-in") ? <LoggedInMp/> : <NotLoggedInMp/>;