Unlike traditional functions, arrow functions do not have their own __________.
- this
- arguments
- return
- parameters
Unlike traditional functions, arrow functions do not have their own this binding. In arrow functions, this retains the value of the enclosing lexical context, which makes it useful in cases where you want to maintain the context of the surrounding code, such as in callbacks or when defining functions within functions.
You're debugging a JavaScript application and notice unexpected behavior in the manipulation of an array. The items are not being removed correctly using a method, and it turns out the array is not being modified at all. Which array method might be mistakenly being used?
- pop()
- push()
- splice()
- concat()
The concat() method is often mistakenly used for removing elements from an array because it doesn't modify the original array but returns a new array instead. The correct method for removing elements from an array is splice() or other methods like pop() or shift().
What is "Promise chaining" in JavaScript?
- A method for nesting multiple if statements
- A technique for connecting multiple Promises
- A way to synchronize asynchronous functions
- A method to define variables
"Promise chaining" is a technique in JavaScript where you can connect multiple Promises together. It allows you to execute asynchronous operations sequentially, making code more readable and manageable, especially when dealing with multiple async tasks.
How does the prototype property behave in arrow functions?
- Arrow functions have a prototype property.
- Arrow functions do not have a prototype.
- Arrow functions inherit their prototype.
- Arrow functions override their prototype.
Arrow functions do not have their own this context and do not have a prototype property. Unlike regular functions, arrow functions do not bind their own this value or have a prototype property. This is a key difference to keep in mind when choosing between regular functions and arrow functions in JavaScript.
Consider a situation where you have a switch statement inside a function, and forgetting to include a break statement leads to a bug. How might this bug manifest in the function’s behavior?
- The function might return the value associated with the first matching case, and all subsequent code within the switch block will execute as well.
- The function will throw an error, indicating a missing "break" statement, and won't execute any code within the switch block.
- The function will automatically insert "break" statements at the end of each case, ensuring correct behavior.
- The function will ignore the switch statement and continue executing the code outside of the switch block.
If you forget to include a "break" statement in a switch case, it will lead to a bug where the function may not behave as expected. Instead of stopping after the first matching case, the switch statement will "fall through" to subsequent cases, causing unintended behavior. The correct option is to use a "break" statement to exit the switch block after handling a case. JavaScript doesn't automatically insert "break" statements, and it doesn't throw an error for missing "break" statements.
Which keyword is used to declare a variable with block scope?
- let
- var
- const
- block
The let keyword is used to declare a variable with block scope in JavaScript. Variables declared with let are limited to the block or scope in which they are defined, which is typically within a pair of curly braces {}.
What will happen if the condition in a while loop is always true?
- The code block will never execute
- The code block will execute once
- An infinite loop will occur
- An error will be thrown
If the condition in a while loop is always true, an infinite loop will occur. The code block will keep executing repeatedly, and the loop will never exit. This can lead to the program becoming unresponsive, and it's essential to ensure that the condition in a while loop eventually becomes false to prevent infinite loops.
What is the impact on performance when using a switch statement versus multiple if-else statements for numerous conditions?
- Switch statements are generally faster than multiple if-else statements for numerous conditions because they use direct lookup tables.
- Switch statements are slower than multiple if-else statements for numerous conditions due to increased code complexity.
- There is no significant difference in performance between switch and if-else statements for numerous conditions.
- Switch statements are slower due to the need for explicit type conversions.
Using a switch statement is often more performant when dealing with numerous conditions because it uses direct lookup tables, making it faster and more efficient than a series of if-else statements, which involve sequential comparisons.
You are developing a system where you have a base class "User" and two derived classes "Admin" and "Guest". If you want to add a method that is only applicable for "Admin" and not for "Guest", where should you add that method to adhere to the Liskov Substitution Principle?
- In the "User" class
- In the "Admin" class
- In the "Guest" class
- In a separate utility function
To adhere to the Liskov Substitution Principle, you should add the method specific to "Admin" in the "Admin" class. This ensures that each derived class (Admin and Guest) can be used interchangeably with the base class (User) without violating the principle.
You are designing a car simulation game using JavaScript. Each type of car (e.g., sedan, truck, etc.) has different methods for calculating fuel efficiency. Which object-oriented programming concept would be most appropriate to ensure that each car type can calculate fuel efficiency in its own way, while still inheriting basic characteristics from a general Car class?
- Inheritance
- Polymorphism
- Encapsulation
- Abstraction
Polymorphism allows different car types (e.g., sedan, truck) to have their own implementations of the fuel efficiency calculation method while inheriting common attributes and behaviors from the general Car class. This ensures flexibility and extensibility in your game.