An object is considered iterable if it implements the _________ method that returns an iterator.
- iterate()
- next()
- loop()
- iterator()
In JavaScript, an object is considered iterable if it implements the next() method, which returns an iterator. The next() method should be used to retrieve the next value in the iteration sequence.
What is the primary purpose of the Symbol type in ES6?
- Representing unique values
- Enhancing string manipulation
- Simplifying arithmetic operations
- Controlling loop iterations
The primary purpose of the Symbol type in ES6 is to represent unique values. Symbols are guaranteed to be unique, and they are often used to create object properties that won't collide with properties of the same name. This uniqueness makes Symbols useful in scenarios where identifier collision is a concern.
In a scenario where you need to process a large array without blocking the event loop, how would a generator function be beneficial?
- Allows asynchronous iteration
- Simplifies event-driven programming
- Enhances parallel processing
- Efficiently manages memory
Generator functions in JavaScript allow asynchronous iteration, which is beneficial in scenarios where you need to process a large array without blocking the event loop. The yield keyword in generators facilitates asynchronous operations, enabling non-blocking code execution.
How does Promise chaining help in handling asynchronous operations?
- It simplifies callback hell by allowing sequential execution of asynchronous tasks.
- It increases the complexity of asynchronous code.
- It only works with synchronous operations.
- It requires additional external libraries.
Promise chaining is a technique that allows sequential execution of asynchronous tasks, making the code more readable and maintainable by avoiding callback hell.
What happens if a method is called on an object that does not define it but its prototype does?
- The method will throw an error
- The method will be executed using the prototype's implementation
- The method will be executed using the object's implementation
- The method will call the constructor of the object
If a method is called on an object that does not define it but its prototype does, the method will be executed using the prototype's implementation. This is a key feature of prototype-based inheritance in JavaScript.
The __________ loop is used to iterate over the elements of an iterable object in JavaScript.
- for...in
- while
- do...while
- for...of
The for...of loop is specifically designed for iterating over the values of an iterable object, providing a concise and readable syntax for iteration. It simplifies the process of iterating over arrays, strings, maps, sets, and other iterable objects.
What are the limitations of using the spread operator for deep cloning complex objects?
- It does not handle circular references well.
- It only works for primitive data types.
- It cannot clone objects with prototype chains.
- It cannot clone functions.
The spread operator is limited in deep cloning when dealing with circular references, making it less suitable for complex object structures. Circular references can result in infinite loops during cloning.
Can Promises help in avoiding callback hell in asynchronous JavaScript code?
- TRUE
- FALSE
- Only in specific cases
- Depends on the browser
Promises play a crucial role in avoiding callback hell in asynchronous JavaScript code. By using promises, you can chain asynchronous operations more cleanly, making the code more readable and maintainable. Option A is correct because Promises are indeed effective in this context.
What distinguishes the Symbol.iterator property in an iterable?
- It uniquely identifies the iterable object
- It defines the iteration logic of the iterable
- It represents the number of iterations
- It is used to check if an object is iterable
In ES6, the Symbol.iterator property is a special symbol used to define the default iterator for an object. The value assigned to this symbol is a function that returns the iterator object, providing the logic for iterating over the object's elements. This allows customizing the iteration behavior for user-defined objects.
In ES6, which method is commonly used as a higher-order function for arrays?
- map()
- concat()
- reduce()
- slice()
The map() method in ES6 is commonly used as a higher-order function for arrays, allowing the transformation of each element with a provided function.