Webpack Code Splitting and Dynamic Imports Quiz Quiz

Deepen your understanding of code splitting and dynamic imports in modern JavaScript with this focused quiz. Explore techniques and benefits of efficient bundling, lazy loading, and dynamic module management to enhance web application performance.

1. Identifying Benefits of Code Splitting

   Which of the following best describes a primary benefit of using code splitting in a web application?

   1. Loading only necessary code for the current user interaction
   2. Increasing the size of delivered JavaScript bundles
   3. Replacing the need for any static imports
   4. Shorter build time for JavaScript source files

   Explanation: The correct answer is 'Loading only necessary code for the current user interaction' because code splitting allows portions of the application code to be loaded on demand, enhancing performance and reducing initial load times. 'Shorter build time for JavaScript source files' is incorrect; code splitting can sometimes slightly increase build time. 'Increasing the size of delivered JavaScript bundles' is the opposite of code splitting's purpose. 'Replacing the need for any static imports' is inaccurate because static imports are still necessary for essential code.

2. Understanding Dynamic Imports

   Given the following code: import('utils/math').then(module =u003E module.add(2, 3)), which concept is being demonstrated?

   1. Tree shaking
   2. Hash chunking
   3. Static importing
   4. Dynamic importing

   Explanation: Dynamic importing is shown here, where modules are loaded asynchronously at runtime. Static importing refers to importing modules at compile-time, not using the import() function. Tree shaking removes unused code but does not handle on-demand loading. Hash chunking is a pattern for naming files and is unrelated to this code syntax.

3. Bundle Generation when Using Dynamic Imports

   When dynamic imports are used in a project, how does the bundler typically handle the resulting JavaScript files?

   1. Ignores dynamically imported modules during the build
   2. Deletes unused dynamic import statements
   3. Generates separate chunk files for dynamically imported modules
   4. Combines all modules into one large bundle

   Explanation: The bundler creates separate chunk files for each dynamically imported module, which are loaded as needed. Combining all modules into one bundle would defeat the purpose of code splitting. Ignoring dynamically imported modules would cause them not to be available at runtime, which is incorrect. Deleting dynamic import statements would break functionality and is not a valid approach.

4. Syntax for Initiating a Dynamic Import

   Which syntax correctly initiates a dynamic import for a file named 'feature.js'?

   1. fetch('feature.js')
   2. import('feature.js')
   3. import 'feature.js'
   4. require('feature.js')

   Explanation: The correct syntax for a dynamic import is using import('feature.js'), which returns a promise when loading the module. 'import 'feature.js'' is static syntax and does not perform code splitting. 'require('feature.js')' is static in some environments, and 'fetch('feature.js')' retrieves the file but does not execute JavaScript as a module.

5. Lazy Loading and User Experience

   How can code splitting and dynamic imports improve user experience in a Single Page Application (SPA)?

   1. By merging all scripts into a single synchronous bundle
   2. By forcing all modules to load before the main page appears
   3. By slowing down navigation due to extra network requests
   4. By reducing initial load times and loading features as needed

   Explanation: Reducing initial load times and loading features as needed allows users to access the main functionality faster and only downloads additional code when required. Merging all scripts into a single bundle does the opposite by increasing load times. Slowing down navigation is not a typical result when code splitting is used correctly. Loading all modules before the main page appears contradicts the principle of code splitting.