Firebase Auth & Realtime Database Apps · 课时

实现电子邮件/密码身份验证

使用 Firebase Authentication，通过电子邮件和密码凭据实现用户注册与登录功能

实现电子邮件/密码身份验证 是 CoddyKit 上的免费 Firebase Auth & Realtime Database Apps 课时。这是第 1 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Firebase Auth & Realtime Database Apps 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Firebase Auth & Realtime Database Apps 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Email/Password Auth Intro

Welcome to implementing user authentication with Firebase! In this lesson, we'll focus on the most common method: Email and Password.

It's straightforward and widely understood by users.
Firebase handles the secure storage of user credentials.
You'll learn to register new users and sign in existing ones.

Enable Email/Password Provider

Before writing code, you need to enable Email/Password authentication in your Firebase project.

Go to the Firebase console:

Navigate to Authentication.
Click on the Sign-in method tab.
Enable the Email/Password provider.

This tells Firebase to accept these credentials.

Registering New Users

To let new users create an account, you'll use a Firebase Authentication method. This method takes an email and a password, then securely creates a new user record in your Firebase project.

It's crucial to gather the user's email and a strong password from your app's UI.

User Registration Code

Here's how you register a new user using the Firebase SDK. We'll use JavaScript syntax, common for web and mobile apps.

createUserWithEmailAndPassword() is the key function.

import { getAuth, createUserWithEmailAndPassword } from "firebase/auth";

const auth = getAuth();

function registerUser(email, password) {
  createUserWithEmailAndPassword(auth, email, password)
    .then((userCredential) => {
      // Signed up successfully
      const user = userCredential.user;
      console.log("User registered:", user.email);
    })
    .catch((error) => {
      const errorCode = error.code;
      const errorMessage = error.message;
      console.error("Registration error:", errorCode, errorMessage);
    });
}

Signing In Existing Users

Once a user has registered, they can sign in using the same email and password. This process verifies their credentials against the stored records in Firebase.

If the credentials match, Firebase provides a user object, indicating a successful login.

User Login Code

To sign in an existing user, you use signInWithEmailAndPassword(). It works similarly to registration, taking an email and password.

This function also returns a Promise, allowing you to handle success or failure.

import { getAuth, signInWithEmailAndPassword } from "firebase/auth";

const auth = getAuth();

function loginUser(email, password) {
  signInWithEmailAndPassword(auth, email, password)
    .then((userCredential) => {
      // Signed in successfully
      const user = userCredential.user;
      console.log("User logged in:", user.email);
    })
    .catch((error) => {
      const errorCode = error.code;
      const errorMessage = error.message;
      console.error("Login error:", errorCode, errorMessage);
    });
}

Accessing Current User Data

After a user successfully registers or logs in, you can access their information via the currentUser object. This object holds details like their unique ID (UID) and email.

It's vital for personalizing app content.

import { getAuth } from "firebase/auth";

const auth = getAuth();

function displayUserInfo() {
  const user = auth.currentUser;

  if (user) {
    // User is signed in
    console.log("User UID:", user.uid);
    console.log("User Email:", user.email);
    // You can also get user.displayName, user.photoURL, etc.
  } else {
    // No user is signed in
    console.log("No user currently logged in.");
  }
}

Logging Users Out

Providing a way for users to sign out is essential for security and user experience. Firebase Auth makes this simple with the signOut() method.

Calling signOut() clears the user's session.

import { getAuth, signOut } from "firebase/auth";

const auth = getAuth();

function logoutUser() {
  signOut(auth).then(() => {
    // Sign-out successful.
    console.log("User signed out successfully!");
  }).catch((error) => {
    // An error happened.
    console.error("Sign out error:", error);
  });
}

Basic Error Handling

When dealing with authentication, errors are common (e.g., wrong password, email already in use). Firebase provides specific error codes and messages.

Always include .catch() blocks to gracefully handle these issues and provide feedback to your users.

import { getAuth, signInWithEmailAndPassword } from "firebase/auth";

const auth = getAuth();

// Example with error handling
signInWithEmailAndPassword(auth, "wrong@example.com", "badpassword")
  .then((userCredential) => {
    console.log("Login successful!");
  })
  .catch((error) => {
    const errorCode = error.code; // e.g., 'auth/user-not-found'
    const errorMessage = error.message; // e.g., 'There is no user record...'
    console.error("Auth failed:", errorCode, errorMessage);
    // Display user-friendly message based on errorCode
  });

Check Your Knowledge

Which Firebase Authentication method is used to create a new user account with an email and password?

Recap: Email/Password Auth

Great job! You've learned the fundamentals of Email/Password authentication with Firebase.

You enable the provider in the Firebase console.
createUserWithEmailAndPassword() registers new users.
signInWithEmailAndPassword() logs in existing users.
currentUser gives you access to user data.
signOut() logs users out.
Always implement error handling for a robust app.

Next, we'll explore managing user sessions and states!

常见问题解答

「实现电子邮件/密码身份验证」课时是免费的吗？

是的 — 「实现电子邮件/密码身份验证」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Firebase Auth & Realtime Database Apps 课程的其余内容，请升级到 CoddyKit PRO。 Firebase Auth & Realtime Database Apps 课程共包含 4 节课。

「实现电子邮件/密码身份验证」这节课中我会学到什么？

使用 Firebase Authentication，通过电子邮件和密码凭据实现用户注册与登录功能你通过在浏览器中直接运行的动手代码来练习 Firebase Auth & Realtime Database Apps，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Firebase Auth & Realtime Database Apps 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Firebase Auth & Realtime Database Apps 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 1 节课，共 4 节。

「实现电子邮件/密码身份验证」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

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能。每节 Firebase Auth & Realtime Database Apps 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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