Which method removes the last element from an array and returns that element?
- shift()
- pop()
- unshift()
- splice()
The pop() method in JavaScript is used to remove the last element from an array and return that element. This is commonly used for tasks like removing the last item from a stack implemented as an array. shift() removes the first element, unshift() adds elements to the beginning, and splice() is used for more complex array manipulation.
To handle both resolve and reject in a single method, you can use the .finally method after a(n) _______ block in asynchronous functions.
- try
- await
- then
- catch
To handle both resolve and reject outcomes in a single method, you can use the .finally() method after a try block in asynchronous functions. This ensures that the provided code block is executed regardless of whether the Promise is resolved or rejected.
Why might recursive function expressions cause issues in certain scenarios?
- They can cause an infinite loop and lead to a stack overflow error.
- They can only be used for mathematical calculations and not for general-purpose recursion.
- They can't access variables from the outer scope.
- They are less efficient than iterative approaches.
Recursive function expressions, if not designed carefully, can cause infinite recursion, which leads to a stack overflow error. Each recursive call adds a new function call to the stack, and if there's no base case to stop the recursion, it will continue indefinitely. It's essential to have a termination condition to prevent such issues.
In which context does the "this" keyword not refer to the object that calls the function?
- Global context
- Method context
- Function context
- Constructor context
The "this" keyword in JavaScript does not refer to the object that calls the function in the global context. In the global context, "this" points to the global object, which is usually the "window" object in browsers. This can be a source of confusion, so it's essential to understand the various contexts in which "this" behaves differently.
What is a closure in JavaScript?
- A secure way to store passwords
- A private function
- A way to handle exceptions
- A function that remembers its lexical scope
A closure in JavaScript is a function that "remembers" its lexical scope, even when it's executed outside that scope. This allows the function to maintain access to variables from its parent scope, creating a powerful mechanism for encapsulation and data privacy.
Which array method adds elements to the beginning of an array?
- push()
- unshift()
- concat()
- splice()
The unshift() method is used to add elements to the beginning of an array. It's particularly useful when you want to insert one or more elements at the start of an existing array without affecting the order of the existing elements. Unlike push(), which adds elements to the end, unshift() works at the beginning.
Who is credited as the main developer behind JavaScript's creation?
- Brendan Eich
- Douglas Crockford
- Linus Torvalds
- Tim Berners-Lee
Brendan Eich is credited as the main developer behind JavaScript's creation. He created JavaScript while working at Netscape Communications in 1995. His contributions to the language's design and development have had a lasting impact on web development.
What is the common problem addressed by using asynchronous code in JavaScript?
- Blocking the main thread
- Memory Leaks
- Code Complexity
- Code Optimization
The common problem addressed by using asynchronous code in JavaScript is the avoidance of blocking the main thread. Blocking the main thread can lead to unresponsive user interfaces, making the application seem slow or frozen. Asynchronous code helps prevent this issue by allowing non-blocking execution of tasks.
You are developing an e-commerce website and want to fetch product details asynchronously to avoid page reloads. Which method might be appropriate for managing successive data retrieval operations in a clean and maintainable manner?
- Promises
- Callbacks
- Async/Await
- Observables
To manage successive data retrieval operations in a clean and maintainable manner, you can use the "Async/Await" approach in JavaScript. Async/Await simplifies asynchronous code and makes it look more like synchronous code, which can significantly enhance code readability and maintainability. It allows you to write asynchronous code in a more sequential style, making it easier to handle multiple asynchronous operations.
Which API allows you to make non-simple requests to another domain in JavaScript, considering the Same-Origin Policy?
- XMLHttpRequest
- JSONP (JSON with Padding)
- CORS (Cross-Origin Resource Sharing)
- WebSocket
CORS (Cross-Origin Resource Sharing) is the API that allows you to make non-simple requests (such as those with custom headers or methods) to another domain in JavaScript while considering the Same-Origin Policy. XMLHttpRequest is an older alternative but has limitations compared to CORS. JSONP is a workaround technique, not an API, and WebSocket is used for full-duplex communication, not for cross-origin requests.