You are tasked with optimizing the build process for a production environment. What considerations should you make regarding the management of dependencies and devDependencies?
- Include all dependencies in devDependencies
- Minimize the use of dependencies
- Exclude devDependencies in production builds
- Always use the latest version of dependencies
In a production build, it's important to exclude devDependencies as they are typically only needed for development and testing. Including them in production builds can increase the size of the application unnecessarily. Option (2) is a good practice, but not directly related to managing dependencies for production. Option (1) is incorrect as including all dependencies in devDependencies is not a best practice for production builds. Option (4) is risky as it may introduce compatibility issues.
How can you create a buffer instance in Node.js?
- new Buffer(10)
- Buffer.alloc(10)
- createBuffer(10)
- buffer.create(10)
In Node.js, you can create a buffer instance using the Buffer.alloc(size) method, where size is the desired size of the buffer in bytes. The new Buffer() constructor is deprecated, and the other options are not valid ways to create a buffer in Node.js.
Which of the following is a common technique used for optimizing database queries?
- Query caching
- Adding more indexes
- Increasing database complexity
- Ignoring query performance
One common technique used for optimizing database queries is query caching. It involves storing frequently used query results in memory, reducing the need to re-execute the same query, and improving response times.
If a package is required for running the tests, it should ideally be listed under ________.
- devDependencies
- dependencies
- peerDependencies
- optionalDependencies
If a package is required for running the tests, it should ideally be listed under devDependencies. This ensures that the testing dependencies are only installed during development and testing phases, keeping the production environment clean from unnecessary packages.
You are designing a logging system in Node.js where multiple loggers are listening to logging events. How would you manage and optimize the event listeners to avoid potential memory leaks?
- event.setMaxListeners(1)
- event.on('log', loggerCallback)
- event.prependListener('log', loggerCallback)
- event.removeListener('log', loggerCallback)
To avoid memory leaks when multiple loggers are listening to logging events, it's crucial to remove listeners when they are no longer needed. The event.removeListener() method should be used to remove specific listeners, ensuring that you free up memory and resources when loggers are no longer required. The other options are related to listener management but do not directly address memory leaks.
In ESLint, the ______ property in the configuration file can be used to define global variables.
- Globals
- Environment
- Globals
- Rules
In ESLint, the globals property in the configuration file is used to define global variables that are accessible throughout your code without triggering linting errors. This allows you to specify variables that are declared externally or provided by the environment. The environment option is used to specify which environments your code runs in, but it's not used to define individual global variables. The rules property is used for configuring ESLint rules.
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.