Which of the following is true regarding built-in middlewares in Express.js?

  • Built-in middlewares cannot be customized or extended.
  • You can modify the behavior of built-in middlewares, but you cannot remove them.
  • Built-in middlewares can be completely disabled if not needed.
  • You can add custom middlewares, but built-in ones cannot be used.
In Express.js, you can completely disable built-in middlewares if they are not needed, allowing for customization and control over the middleware stack.

Which of the following methods in JavaScript will remove the last element from an array and return that element?

  • pop()
  • shift()
  • splice()
  • unshift()
The pop() method in JavaScript is used to remove the last element from an array and return that element. It modifies the original array by removing the last element. The other options (shift(), splice(), and unshift()) are used for different array operations.

In JavaScript, the ______ method is used to iterate over all enumerable properties of an object.

  • for loop
  • forEach
  • while loop
  • iterate
The forEach method is used in JavaScript to iterate over all enumerable properties of an object. It is commonly used with arrays to perform an action on each item. The for loop and while loop are general looping constructs and not specific to object iteration. iterate is not a standard method.

The aud claim in a JWT token represents the ________ for which the JWT is intended.

  • Audience
  • Issuer
  • Expiration
  • Subject
The "aud" (audience) claim in a JWT (JSON Web Token) represents the intended audience for which the JWT is intended. It specifies the recipients or systems that are expected to process the token. The "iss" (issuer) claim (Option 2) identifies the entity that issued the token. The "exp" (expiration) claim (Option 3) indicates the time after which the token should not be accepted. The "sub" (subject) claim (Option 4) typically identifies the subject of the token, often the user or system the token represents.

What is the main purpose of using mocking in unit testing?

  • To simulate the behavior of external dependencies
  • To improve code readability
  • To optimize code execution
  • To enforce code standards
Mocking in unit testing is primarily used to simulate the behavior of external dependencies, such as databases, APIs, or services, so that the unit being tested can be isolated and tested in isolation. This helps ensure that tests focus on the unit's logic without relying on the actual external dependencies.

The spread operator can be used to merge two ______ into a new one, combining their properties.

  • Arrays
  • Objects
  • Strings
  • Functions
The spread operator can be used to merge two "Objects" into a new one, combining their properties. It's a useful way to create a new object with properties from multiple source objects.

You are creating a function that accepts an arbitrary number of arguments and returns an array of those arguments. How would you use the rest operator in this scenario to collect all the passed arguments?

  • (function(...args) { return args; })
  • (function(args) { return args; })
  • (function([...args]) { return args; })
  • (function() { return ...args; })
To create a function that accepts an arbitrary number of arguments and returns an array of those arguments, you would use the rest parameter syntax (...args) in the function's parameter list. This syntax collects all the passed arguments into an array named args. The other options are either incorrect or do not use the rest operator correctly.

What is the significance of the 'backpressure' concept in streams in Node.js?

  • Backpressure ensures that data is not lost when reading from or writing to a stream.
  • Backpressure prevents data from being written to a stream.
  • Backpressure is a measure of stream performance.
  • Backpressure is used to close streams automatically.
The significance of 'backpressure' in streams is that it ensures that data is not lost when reading from or writing to a stream. It allows the consumer of data to control the rate of data flow, preventing buffer overflow and resource exhaustion. The other options do not accurately describe the concept of 'backpressure.'

How can specific error handlers be created to respond to different error types in Express.js?

  • Use the try...catch block
  • Define multiple catch blocks
  • Use the app.error() middleware
  • Utilize the next(err) function with custom error classes
In Express.js, specific error handlers for different error types can be created by utilizing the next(err) function with custom error classes. This allows you to define error-handling middleware that can respond to specific error types based on their custom classes. The other options are not typically used for handling specific error types in Express.js.

Which of the following accurately describes Non-Blocking I/O in Node.js?

  • I/O operations that block the main thread
  • I/O operations that execute concurrently
  • I/O operations that are not supported in Node.js
  • I/O operations that must be executed in a callback
Non-Blocking I/O in Node.js refers to I/O operations that execute concurrently without blocking the main thread. It allows Node.js to perform multiple I/O operations without waiting for each operation to complete. The other options describe blocking I/O or do not accurately describe non-blocking I/O.

You are designing a database schema for an e-commerce application, focusing on optimal performance. How would you design the schema and optimize queries to minimize the load on the database?

  • Use a denormalized schema
  • Implement proper indexing
  • Utilize stored procedures for all queries
  • Avoid using primary keys
To minimize the load on the database in an e-commerce application, implementing proper indexing is crucial. Indexes allow the database to efficiently retrieve data. Denormalized schemas can lead to redundancy and maintenance challenges. While stored procedures can be useful, they are not the primary means of optimizing queries. Avoiding primary keys is not recommended; they are essential for data integrity.

Which fs method would you use to read the contents of a directory?

  • fs.readdir()
  • fs.read()
  • fs.readDir()
  • fs.listDirectory()
To read the contents of a directory in Node.js, you should use the fs.readdir() method. It returns an array of all the file and directory names in the specified directory. The other options are not valid fs methods for this purpose.