I am trying to authorize the site through Firebase, everything works as it should, the data is sent to the Firebase server. But further, in the signIn function, I try to create a h2-element and put the mail data into it, which the user entered and clicked on the Login button (I want the mail to be displayed on the site instead of the name), then an error appears on the line where I highlighted with a red arrow: "autorizationName is null, undefined ", no data is sent to html. I can’t understand why, so help, please, I’m recently studying JS to figure it out.

This can happen if I added one JS script to two HTML pages? That is, index.html and autorization.html to the two I added autorization.js I wanted it to be redirected to the main page when authorizing from one page.

  const login = document.querySelector(".form-login")
  login.addEventListener('click', signIn)

function signIn() {
  const email = document.querySelector(".email").value
  const password = document.querySelector(".password").value
//   e.preventDefault()

  signInWithEmailAndPassword(auth, email, password)
      .then((userCredential) => {
          // Signed in 
          const user = userCredential.user;                        
          console.log("Email firebase: ",  user.email);           

          const user2 = JSON.parse(JSON.stringify(user.email))

          const autorizationName = document.querySelector(".autorization-name__container");
          const autorizationNameTitle = document.createElement("h2");
          autorizationNameTitle.textContent = user2;
          autorizationNameTitle.classList.add("autorization-name__title");
          

          autorizationName.appendChild(autorizationNameTitle); // Error: autorizationName is null, undefined
          window.location.replace("http://192.168.1.65:5500/")  
                 
      })

      .catch((error) => {
          const errorCode = error.code;
          const errorMessage = error.message;
          alert(errorMessage + ", " + errorCode);
      });
  }

Here are screenshots: