React Native architecture (bridge, new architecture) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the role of the Bridge in React Native architecture?

The Bridge connects JavaScript code with native platform code, allowing them to communicate asynchronously and exchange data.

intermediate

What problem does the new React Native architecture aim to solve?

It aims to improve performance and reduce communication overhead between JavaScript and native code by replacing the Bridge with a more direct and synchronous system.

intermediate

Name the three main parts of the new React Native architecture.

The three main parts are: Fabric (UI layer), TurboModules (native modules), and the JavaScript Interface (JSI) for direct communication.

advanced

How does Fabric improve UI rendering in React Native?

Fabric allows synchronous and fine-grained updates to the UI by integrating with the native rendering system directly, making UI updates faster and smoother.

advanced

What is the JavaScript Interface (JSI) in the new React Native architecture?

JSI is a lightweight interface that enables direct calls between JavaScript and native code without going through the Bridge, improving speed and reducing latency.

What does the Bridge in React Native do?

A Connects JavaScript and native code asynchronously

B Renders UI components directly

C Manages app navigation

D Handles network requests

The Bridge connects JavaScript and native code asynchronously to allow communication.

Which part of the new architecture handles UI rendering?

A TurboModules

B Fabric

C JSI

D Bridge

Fabric is the UI layer in the new React Native architecture.

What is a key benefit of the new React Native architecture over the old Bridge?

A Slower communication

B More asynchronous calls

C Direct and faster communication

D Less native code

The new architecture enables direct and faster communication between JavaScript and native code.

TurboModules in the new architecture are responsible for:

A Network requests

B UI rendering

C JavaScript parsing

D Native module management

TurboModules manage native modules with improved performance.

JSI stands for:

A JavaScript Interface

B JavaScript Integration

C JavaScript Interpreter

D JavaScript Injection

JSI means JavaScript Interface, enabling direct calls between JS and native code.

Explain how the Bridge works in React Native and why the new architecture replaces it.

Think about how communication speed affects app performance.

Describe the roles of Fabric, TurboModules, and JSI in the new React Native architecture.

Each part improves a specific area of the app.

Practice

1. What is the main role of the bridge in React Native architecture?

easy

A. It manages the app's navigation stack.

B. It compiles JavaScript into native machine code.

C. It connects JavaScript code with native platform code.

D. It handles styling and layout of components.

Solution

1. Step 1: Understand the bridge concept

   The bridge acts as a communication layer between JavaScript and native code in React Native.

2. Step 2: Identify the bridge's role

   It allows JavaScript to send commands and receive data from native modules, enabling cross-platform functionality.

3. Final Answer:

   It connects JavaScript code with native platform code. -> Option C

4. Quick Check:

   Bridge = Connect JS and native [OK]

Hint: Bridge links JS and native code in React Native [OK]

Common Mistakes:

• Thinking bridge compiles JavaScript
• Confusing bridge with navigation or styling
• Assuming bridge handles UI rendering directly

2. Which of the following is the correct way to describe the new React Native architecture?

easy

A. It removes the need for native code entirely.

B. It replaces JavaScript with a new language.

C. It uses a webview to render all components.

D. It improves performance by reducing bridge overhead.

Solution

1. Step 1: Recall the new architecture goal

   The new React Native architecture aims to make apps faster by optimizing communication.

2. Step 2: Understand how it improves performance

   It reduces the overhead caused by the bridge, making interactions between JS and native code more efficient.

3. Final Answer:

   It improves performance by reducing bridge overhead. -> Option D

4. Quick Check:

   New architecture = less bridge overhead [OK]

Hint: New architecture reduces bridge overhead for speed [OK]

Common Mistakes:

• Believing it removes native code completely
• Thinking it replaces JavaScript language
• Confusing it with webview-based rendering

3. Given the following code snippet, what will happen when the JavaScript calls NativeModules.ExampleModule.getData() in React Native's old architecture?

medium

A. The call is sent over the bridge asynchronously.

B. The call goes directly to native code without delay.

C. The call causes a syntax error in JavaScript.

D. The call is handled by a webview component.

Solution

1. Step 1: Understand NativeModules call behavior

   In old React Native, calls to native modules go through the bridge asynchronously.

2. Step 2: Identify the effect of the bridge

   The bridge queues and sends messages between JS and native code, causing asynchronous behavior.

3. Final Answer:

   The call is sent over the bridge asynchronously. -> Option A

4. Quick Check:

   Old architecture calls = async bridge [OK]

Hint: Old architecture uses async bridge calls [OK]

Common Mistakes:

• Assuming direct synchronous native calls
• Thinking it causes syntax errors
• Confusing with webview handling

4. You notice your React Native app is slow due to many bridge calls. Which change can help fix this performance issue?

medium

A. Rewrite all JavaScript code in TypeScript.

B. Switch to the new architecture with TurboModules and Fabric.

C. Remove all native modules and use only JavaScript.

D. Use a webview to render the entire app.

Solution

1. Step 1: Identify cause of slowness

   Many bridge calls cause overhead and slow down the app.

2. Step 2: Choose the right fix

   The new architecture uses TurboModules and Fabric to reduce bridge overhead and improve speed.

3. Final Answer:

   Switch to the new architecture with TurboModules and Fabric. -> Option B

4. Quick Check:

   New architecture reduces bridge calls [OK]

Hint: Use new architecture to reduce bridge calls [OK]

Common Mistakes:

• Thinking TypeScript improves bridge performance
• Removing native modules breaks functionality
• Using webview slows app further

5. How does the new React Native architecture improve UI rendering performance compared to the old bridge system?

hard

A. By using Fabric to directly manage UI components on the native side.

B. By compiling JavaScript into native code at build time.

C. By removing the need for any native code in the app.

D. By rendering UI inside a webview for faster updates.

Solution

1. Step 1: Understand Fabric's role

   Fabric is the new rendering system that manages UI components natively.

2. Step 2: Compare with old bridge system

   Old system sent UI updates over the bridge causing delays; Fabric reduces this by direct native management.

3. Final Answer:

   By using Fabric to directly manage UI components on the native side. -> Option A

4. Quick Check:

   Fabric improves UI by native management [OK]

Hint: Fabric manages UI natively for speed [OK]

Common Mistakes:

• Thinking JavaScript is compiled to native code
• Believing native code is removed
• Confusing Fabric with webview rendering