The for…of statement creates a loop iterating over ________ objects in JavaScript.
- enumerable
- all
- array-like
- visible
The for...of statement in JavaScript creates a loop that iterates over array-like objects, which include arrays, strings, maps, sets, and other objects that have iterable properties. It's particularly useful for iterating over the values of such objects.
In Node.js, the Event Loop operates on a single ________, which makes it suitable for I/O-bound tasks.
- Thread
- Core
- Process
- Module
In Node.js, the Event Loop operates on a single Core, not a thread or process. This single-threaded event loop design is one of the key features of Node.js, making it suitable for I/O-bound tasks as it can efficiently handle asynchronous operations without the overhead of multiple threads or processes.
The concept of defining a blueprint for the data in the database is known as ________.
- Schema
- Query
- Index
- Aggregate
The concept of defining a blueprint for the data in the database is known as "Schema." A schema defines the structure, relationships, constraints, and integrity rules of the data stored in a database.
When an EventEmitter instance experiences an error, the typical event that is emitted is ______.
- 'error'
- 'exception'
- 'fail'
- 'warning'
In Node.js, when an EventEmitter instance experiences an error, the typical event that is emitted is 'error'. This event allows you to handle errors that occur within event listeners attached to the EventEmitter.
How does the closure concept relate to higher-order functions in JavaScript?
- Closures are only used in lower-order functions.
- Higher-order functions cannot create closures.
- Higher-order functions often return closures, allowing them to encapsulate and manage private data.
- Closures are unrelated to higher-order functions.
Closures and higher-order functions are closely related in JavaScript. Higher-order functions often return closures, which can encapsulate and manage private data, creating a powerful mechanism for maintaining state and data privacy.
If an error is not handled by custom error-handling middleware in Express, it is handled by the ______.
- next()
- defaultErrorHandler
- express.handleError()
- console.error()
If an error is not handled by custom error-handling middleware in Express, it is handled by the default Express error handler, which is often referred to as the "defaultErrorHandler." This handler sends an error response to the client and logs the error details.
How does the spread operator behave when used with JavaScript objects that have the same properties?
- It merges the properties, with the values of the second object overwriting the values of the first object.
- It throws an error because objects with the same properties cannot be spread.
- It combines the properties into an array.
- It creates a new object with the properties of the first object only.
When the spread operator (...) is used on objects with the same properties, it merges the properties, with the values of the second object overwriting the values of the first object. This behavior is known as object property spreading.
When using Promise.allSettled, the returned array consists of objects, each having a status property that can either be 'fulfilled' or ________.
- 'completed'
- 'resolved'
- 'rejected'
- 'done'
When using Promise.allSettled, the status property of each object in the returned array can either be 'fulfilled' or 'rejected,' depending on the outcome of the individual Promises in the input array.
In a Node.js module, properties added to the global object can be accessed from ________.
- anywhere in the module
- only within the module
- any other module
Properties added to the global object in a Node.js module can be accessed from anywhere in the module, making them globally accessible within that module.
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.