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.
What is the significance of test coverage in a codebase, and how does it impact the development process?
- Test coverage measures the number of lines of code tested; High test coverage guarantees a bug-free codebase; Test coverage is irrelevant for development.
- Test coverage measures the percentage of code executed by tests; It helps identify untested code paths and potential bugs; High test coverage is a valuable metric but doesn't guarantee bug-free code.
- Test coverage measures the number of test cases written; High test coverage means exhaustive testing and zero defects; Test coverage should be minimized to save development time.
- Test coverage is the number of test tools used; High test coverage indicates a comprehensive testing suite; Test coverage depends on project size.
Test coverage measures the percentage of code executed by tests. It helps identify untested code paths, improving code quality. However, it does not guarantee a bug-free codebase, as it depends on the quality of the tests. The other options provide inaccurate definitions or misconceptions about test coverage.
When creating a custom error class in Express.js, it should extend the built-in ______ class.
- Error
- HttpException
- AppError
- CustomError
When creating a custom error class in Express.js, it should extend the built-in Error class. This allows you to leverage the error handling capabilities provided by JavaScript and Express.js. Extending other classes like HttpException, AppError, or CustomError is not a standard practice for custom error classes in Express.js.