You are developing a large-scale application and notice that some modules are loading slowly. How would you optimize the loading of modules to improve the application's performance?
- Minify and bundle all modules into a single file.
- Use lazy loading to load modules on-demand.
- Increase server hardware resources.
- Reduce the number of modules.
To optimize the loading of modules in a large-scale application, you should use lazy loading (Option b). Lazy loading allows modules to be loaded only when they are needed, reducing initial load times and improving performance. Minification (Option a) is also a valid optimization technique but may not address the issue of slow initial loading. Increasing server resources (Option c) and reducing the number of modules (Option d) are not effective solutions for optimizing module loading.
You are tasked with creating an API endpoint that should respond to multiple HTTP methods (GET, POST) and have optional parameters. How would you efficiently implement this in Express.js?
- Use app.all('/endpoint', handler)
- Create separate route handlers for each HTTP method and parameter combination
- Implement a single route handler and use conditional logic to handle methods and parameters
- Define multiple endpoints for each combination of HTTP methods and parameters
In Express.js, an efficient way to handle multiple HTTP methods and optional parameters is to implement a single route handler and use conditional logic to differentiate between methods and handle optional parameters within the handler. This approach minimizes code duplication and keeps your codebase clean and maintainable. Using app.all (Option 1) would capture all HTTP methods and may lead to less control and more complex code. Separating handlers for each combination (Option 2) can result in code redundancy, making it harder to maintain. Creating multiple endpoints (Option 4) can lead to a cluttered route structure.
What considerations should be made while implementing asynchronous middleware in Express.js?
- Asynchronous middleware should use the await keyword to ensure proper execution flow.
- Asynchronous middleware should always return a Promise or use a callback.
- Asynchronous middleware should not be used in Express.js as it can lead to performance issues.
- Asynchronous middleware should use the sync keyword to ensure proper execution flow.
When implementing asynchronous middleware in Express.js, it's crucial to ensure that the middleware either returns a Promise or uses a callback to signal when it has completed its work. This is necessary to prevent premature termination of the request-response cycle and maintain proper error handling. Using await is a common approach to handling asynchronous operations.
In case a package should be uninstalled and also removed from the package.json, the ______ command should be executed.
- npm remove
- npm uninstall
- npm erase
- npm discard
To uninstall a package and also remove it from the package.json file, you should use the npm uninstall (or npm remove) command followed by the package name. This command removes both the package and its reference from package.json. The other options are not used for this specific purpose.
In Jest, to isolate a module from its dependencies for more focused unit testing, you would use ______.
- mock
- stub
- spy
- inject
In Jest, you can use the mock function to isolate a module from its dependencies. This allows you to replace the real dependencies with mock implementations for focused unit testing.
When using the rest operator in a function’s parameters, it will collect the remaining arguments into an ______.
- Array
- Object
- String
- Argument
When using the rest operator (...) in a function's parameters, it will collect the remaining arguments into an "Array." This allows you to work with variable-length argument lists easily.
How does Non-Blocking I/O facilitate the development of scalable applications in Node.js?
- It allows multiple I/O operations to be executed concurrently without blocking the main thread.
- It forces all I/O operations to be executed sequentially, which improves predictability.
- It has no impact on application scalability.
- It reduces the number of I/O operations that can be performed concurrently.
Non-Blocking I/O in Node.js enables the execution of multiple I/O operations concurrently without blocking the main thread. This concurrency is essential for developing scalable applications that can handle numerous incoming requests simultaneously.
You are developing an Express.js application and you realize that some of the errors are not being caught by your error-handling middleware. What should you consider while debugging this issue?
- Check the order of middleware execution
- Increase the stack size of the Node.js process
- Disable error handling for those specific routes
- Increase the timeout for asynchronous operations
In Express.js, middleware functions are executed in the order they are defined. If some errors are not being caught by your error-handling middleware, it's crucial to check the order of middleware execution. Errors should be handled after they are thrown, so make sure your error-handling middleware comes after the routes that might throw errors.
Using the BigInt data type, you can represent integers larger than ______.
- 2^31 - 1
- 2^53 - 1
- 2^63 - 1
- 2^128 - 1
Using the BigInt data type in JavaScript, you can represent integers larger than 2^128 - 1. BigInts are not restricted by the usual 53-bit limit of regular JavaScript numbers (doubles), allowing you to work with much larger integers.
Which of the following can be considered as a performance bottleneck in a web application?
- High network latency
- Code comments
- Proper error handling
- Modular code structure
High network latency can be considered a performance bottleneck in a web application. Slow data transfer between the client and server due to network latency can significantly impact the application's performance. Code comments, proper error handling, and modular code structure, while important for code quality, are not typically performance bottlenecks.