title: I Want To Check If User Exist Before Login If Not They Must Sign Up, In Firebase Google Auth
body: <p>I have Login and Sign Up functionality using Firebase Google Auth and It works Fine but I want to Check If the user already Signed Up, They can't sign Up 2 times they'll have to Login. is there a Code Like:</p>
  <pre><code>if(user.exist){
    alert(&quot;Account Already exists please Login&quot;)
  }else{
    auth.signInWithPopup(provider)
  }
  </code></pre>
  <p>And vice versa if they do not exist they'll have to Sign Up:</p>
  <p>Is This possible with google auth?</p>