React Tutorial: User Auth with Authgear SDK

Follow this quickstart tutorial to add authentication to your React application
Authgear helps you add user logins to your React apps. It provides prebuilt login page and user settings page that accelerate the development.
Follow this 🕐
 15 minutes tutorial to create a simple app using React with Authgear SDK.
Check out and clone the Sample Project on GitHub.
Table of Content
​Setup Application in Authgear​
​Create a simple React project​
​Install Authgear SDK to the project​
​Implement Context Provider​
​Implement the Auth Redirect page​
​Add a Login button​
​Show the user information​
​Add a Logout button​
​Open User Settings​
​Calling an API​
Setup Application in Authgear
Signup for an account in https://portal.authgearapps.com/ and create a Project.
After that, we will need to create an Application in the Project Portal.
Create an application in the Portal
1.Go to Applications on the left menu bar.
2.Click ⊕Add Application in the top tool bar.
3.Input the name of your application, e.g. "MyAwesomeApp".
4.Select Single Page Application as the application type 
5.Click "Save" to create the application
Configure Authorize Redirect URI
The Redirect URI is a URL in you application where the user will be redirected to after login with Authgear. In this path, make a finish authentication call to complete the login process. 
For this tutorial, add http://localhost:4000/auth-redirect to Authorize Redirect URIs.
Configure Post Logout Redirect URI
The Post Logout Redirect URI is the URL users will be redirected after they have logged out. The URL must be whitelisted.
For this tutorial, add http://localhost:4000/ to Post Logout Redirect URIs.
Save the configuration before next steps.
Configure Authorized Redirect URIs and Post Logout Redirect URIs.
Step 1: Create a simple React project
Here are some recommended steps to scaffold a React project. You can skip this part if you are adding Authgear to an existing project. See install-authgear-sdk-to-the-project in the next section.
Install basic project dependencies
Create the project folder and install the dependencies. We will use parcel as the build tool and the react-router-dom, react , and react-dom packages. Also, we will use TypeScript in this tutorial. 
# Create a new folder for your project
mkdir my-app
# Move into the project directory
cd my-app
# Create source folder
mkdir src
# Create a brand new package.json file
npm init -y
# Install parcel
npm install --save-dev --save-exact parcel
# Install react, react-dom and react router
npm install --save-exact react react-dom react-router-dom
# Install TypeScript and related types
npm install --save-dev --save-exact typescript @types/react @types/react-dom @types/react-router-dom
Add script for launching the app
In the package.json file, add these two lines to the script section
"start": "parcel serve --port 4000 --no-cache ./src/index.html",
"build": "parcel build --no-cache ./src/index.html"
The start script run the app in development mode on port 4000. The build script build the app for production to the dist/ folder.
Create the index.html file
In src/, create a new file called index.html for parcel to bundle the app: 
src/index.html:
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <title>Authgear React Tutorial Demo App</title>
  </head>
  <body>
    <div id="react-app-root"></div>
    <script type="module" src="./index.tsx"></script>
  </body>
</html>
​
Create the App.tsx file
Create a new file called App.tsx with simply showing Hello World in the screen: 
// src/App.tsx
import React from "react";
​
const App: React.FC = () => {
  return <div>Hello World</div>;
};
​
export default App;
​
Create the index.tsx file
Create a new file called index.tsx as the entry point of the application.
// src/index.tsx
import React from "react";
import { createRoot } from "react-dom/client";
import App from "./App";
​
async function init() {
  try {
   // initialization code
  } finally {
    createRoot(document.getElementById("react-app-root")!).render(<App />);
  }
}
​
init().catch((e) => {
  // Error handling
  console.error(e)
});
 
The file structure in your project is now:
my-app
├── node_modules
│   └── (...)
├── package-lock.json
├── package.json
└── src
    ├── App.tsx
    ├── index.html
    └── index.tsx
Run npm start now to run the project and you will see "Hello World" on http://localhost:4000.
Step 2: Install Authgear SDK to the project
Run the following command within your React project directory to install the Authgear Web SDK
npm install --save --save-exact @authgear/web
In src/index.tsx , import authgear and call the configure function to initialize an Authgear instance on application loads.
// src/index.tsx
import React from "react";
import { createRoot } from "react-dom/client";
import App from "./App";
import authgear from "@authgear/web";
​
async function init() {
  try {
    // configure Authgear container instance
    await authgear.configure({
      endpoint: "<your_app_endpoint>",
      clientID: "<your_client_id>",
      sessionType: "refresh_token",
    });
  } finally {
    createRoot(document.getElementById("react-app-root")!).render(<App />);
  }
}
​
init().catch((e) => {
  // Error handling
  console.error(e)
});
The Authgear container instance takes endpoint and clientID as parameters. They can be obtained from the application page created in Setup Application in Authgear.
It is recommend to render the app after configure() resolves. So by the time the app is rendered, Authgear is ready to use. 
Run npm start now and you should see a page with "Hello World" and no error message in the console if Authgear SDK is configured successfully
Step 3: Implement the Context Provider
Since we want to reference the logged in state in anywhere of the app, let's put the state in a context provider with UserProvider.tsx in the /src/context folder. 
In UserProvider.tsx, it will have a isLoggedIn boolean and a setIsLoggedIn function. The is LoggedIn boolean state can be auto updated using the onSessionStateChange callback. This callback can be stored in delegate which is in the local SDK container. 
// src/context/UserProvider.tsx
import React, { createContext, useEffect, useState, useMemo } from "react";
import authgear from "@authgear/web";
​
interface UserContextValue {
  isLoggedIn: boolean;
}
​
export const UserContext = createContext<UserContextValue>({
  isLoggedIn: false,
});
​
interface UserContextProviderProps {
  children: React.ReactNode;
}
​
const UserContextProvider: React.FC<UserContextProviderProps> = ({
  children,
}) => {
  // By default the user is not logged in
  const [isLoggedIn, setIsLoggedIn] = useState<boolean>(false);
​
  useEffect(() => {
    // When the sessionState changed, logged in state will also be changed
    authgear.delegate = {
      onSessionStateChange: (container) => {
        // sessionState is now up to date
        // Value of sessionState can be "NO_SESSION" or "AUTHENTICATED"
        const sessionState = container.sessionState;
        if (sessionState === "AUTHENTICATED") {
          setIsLoggedIn(true);
        } else {
          setIsLoggedIn(false);
        }
      },
    };
  }, [setIsLoggedIn]);
​
  const contextValue = useMemo<UserContextValue>(() => {
    return {
      isLoggedIn,
    };
  }, [isLoggedIn]);
​
  return (
    <UserContext.Provider value={contextValue}>{children}</UserContext.Provider>
  );
};
​
export default UserContextProvider;
​
Step 4: Implement the Auth Redirect
Next, we will add an "AuthRedirect" page for handling the authentication result after the user have been authenticated by Authgear.
Create the AuthRedirect.tsx component file in the src/ folder. 
Call the Authgear finishAuthentication() function in the Auth Redirect component to send a token back to Authgear server in exchange for access token and refresh token. Don't worry about the technical jargons, finishAuthentication() will do all the hard work for you and and save the authentication data.
When the authentication is finished, the isLoggedIn state from the UserContextProvider will automatic set to true.  Finally, navigate back to root (/) which is our Home page.
The final AuthRedirect.tsx will look like this
// src/AuthRedirect.tsx
import React, { useEffect, useRef } from "react";
import { useNavigate } from "react-router-dom";
import authgear from "@authgear/web";
​
const AuthRedirect: React.FC = () => {
  const usedToken = useRef(false);
​
  const navigate = useNavigate();
​
  useEffect(() => {
    async function updateToken() {
      try {
        await authgear.finishAuthentication();
      } finally {
        navigate("/");
        usedToken.current = true;
      }
    }
​
    if (!usedToken.current) {
      updateToken().catch((e) => console.error(e));
    }
  }, [navigate]);
​
  return <></>;
};
​
export default AuthRedirect;
​
Since in React 18, useEffect will be fired twice in development mode, we need to implement a cleanup function to stop it from firing twice. We will use an useRef Hook to stop the user token from being sent twice to the Authgear Endpoint.
Without a cleanup function, anuseEffectHook will be fired twice and hence finishAuthentication() will send the token back to Authgear Endpoint for two times, which the second one will result in "Invalid Token" error since the token can only be used once.
Step 5: Add Routes and Context Provider to the App
Next, we will add a "Home" page . Create a Home.tsx component file the src/ folder. 
Then import Home and AuthRedirect as routes. And Import UserContextProvider and wrap the routes with it.
Your final App.tsx should look like this:
// src/App.tsx
import React from "react";
import { BrowserRouter as Router, Routes, Route } from 'react-router-dom';
import Home from './Home';
import AuthRedirect from './AuthRedirect';
import UserContextProvider from './context/UserProvider';
​
const App: React.FC = () => {
  return (
    <UserContextProvider>
      <Router>
        <Routes>
          <Route path="/auth-redirect" element={<AuthRedirect />} />
          <Route path="/" element={<Home />} />
        </Routes>
      </Router>
    </UserContextProvider>
  );
}
​
export default App;
​
The file structure should now look like
src
├── App.tsx
├── AuthRedirect.tsx
├── Home.tsx
├── context
│   └── UserProvider.tsx
├── index.html
└── index.tsx
Step 6: Add a Login button
First we will import the Authgear dependency and the React Hook that we will use to Home.tsx. Then add the login button which will call startAuthentication(ConfigureOptions) through startLogin callback on click. This will redirect the user to the login page.
// src/Home.tsx
import React, { useEffect, useState, useCallback, useContext } from 'react';
import authgear from '@authgear/web';
​
const Home: React.FC = () => {
  const startLogin = useCallback(() => {
    authgear
      .startAuthentication({
        redirectURI: 'http://localhost:4000/auth-redirect',
        prompt: 'login'
      })
      .then(
        () => {
          // started authentication, user should be redirected to Authgear
        },
        err => {
          // failed to start authentication
        }
      );
  }, []);
  return (
    <div>
      <h1>Home Page</h1>
      <div>
        <button onClick={startLogin}>Login</button>
      </div>
    </div>
  );
}
​
export default Home;
​
You can now run npm start and you will be redirected to the Authgear Login page when you click the Login button.
User will be redirected to the Authgear login page by clicking the login button
Step 7: Show the user information
The Authgear SDK helps you get the information of the logged in users easily.
In the last step, the user is successfully logged in so let's try to print the user ID (sub) of the user in the Home page.
In Home.tsx, we will add a simple Loading splash and a greeting message printing the Sub ID. We will add two conditional elements such that they are only shown when user is logged in. We can also change the login button to show only if the user is not logged in. 
Make use of isLoggedIn from the UserContext to control the components on the page. Fetch the user info by fetchInfo() and access its sub property.
// src/Home.tsx  
import React, { useEffect, useState, useCallback, useContext } from "react";
import authgear from "@authgear/web";
import { UserContext } from "./context/UserProvider";
​
const Home: React.FC = () => {
  const [greetingMessage, setGreetingMessage] = useState<string>("");
  const [isLoading, setIsLoading] = useState<boolean>(false);
  const { isLoggedIn } = useContext(UserContext);
​
  useEffect(() => {
    async function updateGreetingMessage() {
      setIsLoading(true);
      try {
        if (isLoggedIn) {
          const userInfo = await authgear.fetchUserInfo();
          setGreetingMessage("The current User sub: " + userInfo.sub);
        }
      } finally {
        setIsLoading(false);
      }
    }
​
    updateGreetingMessage().catch((e) => {
      console.error(e);
    });
  }, [isLoggedIn]);
​
  const startLogin = useCallback(() => {
    authgear
      .startAuthentication({
        redirectURI: "http://localhost:4000/auth-redirect",
        prompt: "login",
      })
      .then(
        () => {
          // started authentication, user should be redirected to Authgear
        },
        (err) => {
          // failed to start authentication
        }
      );
  }, []);
​
  return (
    <div>
      <h1>Home Page</h1>
      {isLoading && "Loading"}
      {greetingMessage ? <span>{greetingMessage}</span> : null}
      {!isLoggedIn && (
        <div>
          <button type="button" onClick={startLogin}>
            Login
          </button>
        </div>
      )}
    </div>
  );
};
​
export default Home;
Run the app again, the User ID (sub) of the user should be printed on the Home page.
Step 8: Add a Logout button
Finally, let's add an Logout button when user is logged in. 
In Home.tsx, we will add a conditional elements in the elements:
{isLoggedIn && (
  <div>
    <button onClick={logout}>Logout</button>
  </div>
)}
And add the logout callback:
const logout = useCallback(() => {
  authgear
    .logout({
      redirectURI: "http://localhost:4000/",
    })
    .then(
      () => {
        setGreetingMessage('');
      },
      (err) => {
        console.error(err);
      }
  );
}, []);
Run the app again, we can now logout by clicking the logout button.
Step 9: Open User Settings
Authgear provide a built-in UI for the users to set their attributes and change security settings. 
Use the openURL function to open the setting page at <your_app_endpoint>/settings
In Home.tsx Add a conditional link to the elements.
{isLoggedIn && (
  <a target="_blank" rel="noreferrer" onClick={userSetting} href="#">
    User Setting
  </a>
)}
And add the userSetting callback:
import authgear, { Page } from "@authgear/web";
const userSetting = useCallback((e: React.MouseEvent<HTMLAnchorElement>) => {
    e.preventDefault();
    e.stopPropagation();
    authgear.open(Page.Settings);
}, []);
This the the resulting Home.tsx:
// src/Home.tsx
import React, { useEffect, useState, useCallback, useContext } from "react";
import { UserContext } from "./context/UserProvider";
import authgear, { Page } from "@authgear/web";
​
const Home: React.FC = () => {
  const [greetingMessage, setGreetingMessage] = useState<string>("");
  const [isLoading, setIsLoading] = useState<boolean>(false);
  const { isLoggedIn } = useContext(UserContext);
​
  useEffect(() => {
    async function updateGreetingMessage() {
      setIsLoading(true);
      try {
        if (isLoggedIn) {
          const userInfo = await authgear.fetchUserInfo();
          setGreetingMessage("The current User sub: " + userInfo.sub);
        }
      } finally {
        setIsLoading(false);
      }
    }
​
    updateGreetingMessage().catch((e) => {
      console.error(e);
    });
  }, [isLoggedIn]);
​
  const startLogin = useCallback(() => {
    authgear
      .startAuthentication({
        redirectURI: "http://localhost:4000/auth-redirect",
        prompt: "login",
      })
      .then(
        () => {
          // started authorization, user should be redirected to Authgear
        },
        (err) => {
          // failed to start authorization
          console.error(err);
        }
      );
  }, []);
​
  const logout = useCallback(() => {
    authgear
      .logout({
        redirectURI: "http://localhost:4000/",
      })
      .then(
        () => {
          setGreetingMessage("");
        },
        (err) => {
          console.error(err);
        }
      );
  }, []);
​
  const userSetting = useCallback((e: React.MouseEvent<HTMLAnchorElement>) => {
    e.preventDefault();
    e.stopPropagation();
    authgear.open(Page.Settings);
  }, []);
​
  return (
    <div>
      {/* eslint-disable-next-line react/forbid-elements */}
      <h1>Home Page</h1>
      {isLoading && "Loading"}
      {greetingMessage ? <span>{greetingMessage}</span> : null}
      {!isLoggedIn && (
        <div>
          <button type="button" onClick={startLogin}>
            Login
          </button>
        </div>
      )}
      {isLoggedIn && (
        <div>
          <button type="button" onClick={logout}>
            Logout
          </button>
          <br />
          <a target="_blank" rel="noreferrer" onClick={userSetting} href="#">
            User Setting
          </a>
        </div>
      )}
    </div>
  );
};
​
export default Home;
Show the User ID, a link to User Settings and a logout button after login
Next steps, Calling an API
To access restricted resources on your backend application server, the HTTP requests should include the access token in their Authorization headers. The Web SDK provides a fetch function which automatically handle this, or you can get the token with authgear.accessToken.
Option 1: Using fetch function provided by Authgear SDK
Authgear SDK provides the fetch function for you to call your application server. This fetch function will include the Authorization header in your application request, and handle refresh access token automatically. The authgear.fetch implements fetch.
authgear
    .fetch("YOUR_SERVER_URL")
    .then(response => response.json())
    .then(data => console.log(data));
Option 2: Add the access token to the HTTP request header
You can get the access token through authgear.accessToken. Call refreshAccessTokenIfNeeded every time before using the access token, the function will check and make the network call only if the access token has expired. Include the access token into the Authorization header of the application request.
authgear
    .refreshAccessTokenIfNeeded()
    .then(() => {
        // access token is ready to use
        // accessToken can be string or undefined
        // it will be empty if user is not logged in or session is invalid
        const accessToken = authgear.accessToken;
​
        // include Authorization header in your application request
        const headers = {
            Authorization: `Bearer ${accessToken}`
        };
    });