How to fix auth/weak-password in Firebase

// Example: Password validation check
const password = "12345"; // Only 5 characters - will be rejected
// This will throw error code: auth/weak-password

// Web - JavaScript
function validatePassword(password) {
  const minLength = 6;
  if (password.length < minLength) {
    return {
      isValid: false,
      message: `Password must be at least ${minLength} characters`,
    };
  }
  return { isValid: true };
}

// When creating user
const auth = firebase.auth();
const email = "[email protected]";
const password = "MyPassword123";

const validation = validatePassword(password);
if (!validation.isValid) {
  console.error(validation.message);
  return;
}

auth
  .createUserWithEmailAndPassword(email, password)
  .then((userCredential) => {
    console.log("User created:", userCredential.user.uid);
  })
  .catch((error) => {
    if (error.code === "auth/weak-password") {
      console.error("Password is too weak");
    }
  });

// Web - JavaScript
firebase
  .auth()
  .createUserWithEmailAndPassword(email, password)
  .catch((error) => {
    if (error.code === "auth/weak-password") {
      displayUserMessage("Password must be at least 6 characters");
    } else if (error.code === "auth/email-already-in-use") {
      displayUserMessage("Email is already registered");
    }
  });

// Flutter - Dart
try {
  await FirebaseAuth.instance.createUserWithEmailAndPassword(
    email: email,
    password: password,
  );
} on FirebaseAuthException catch (e) {
  if (e.code == "weak-password") {
    print("The password is too weak: ${e.message}");
  }
}

// Android - Java
mAuth
  .createUserWithEmailAndPassword(email, password)
  .addOnCompleteListener(
    task -> {
      if (!task.isSuccessful()) {
        if (task.getException() instanceof FirebaseAuthWeakPasswordException) {
          String reason = ((FirebaseAuthWeakPasswordException) task.getException()).getReason();
          Toast.makeText(context, "Weak password: " + reason, Toast.LENGTH_SHORT).show();
        }
      }
    });

<form id="signup-form">
  <label for="email">Email:</label>
  <input type="email" id="email" required />

  <label for="password">Password:</label>
  <input type="password" id="password" required />

  <div id="password-requirements">
    <p>Password must:</p>
    <ul>
      <li id="req-length">
        <span id="check-length">✗</span> Be at least 6 characters
      </li>
      <li id="req-uppercase">
        <span id="check-uppercase">✗</span> Include an uppercase letter
      </li>
      <li id="req-lowercase">
        <span id="check-lowercase">✗</span> Include a lowercase letter
      </li>
      <li id="req-number">
        <span id="check-number">✗</span> Include a number
      </li>
    </ul>
  </div>

  <button type="submit">Sign Up</button>
</form>

<script>
  const passwordInput = document.getElementById("password");

  passwordInput.addEventListener("input", (e) => {
    const pwd = e.target.value;

    document.getElementById("check-length").textContent =
      pwd.length >= 6 ? "✓" : "✗";
    document.getElementById("check-uppercase").textContent =
      /[A-Z]/.test(pwd) ? "✓" : "✗";
    document.getElementById("check-lowercase").textContent =
      /[a-z]/.test(pwd) ? "✓" : "✗";
    document.getElementById("check-number").textContent =
      /[0-9]/.test(pwd) ? "✓" : "✗";
  });
</script>