What is the purpose of the prototype chain in JavaScript?
- To store local variables
- To manage asynchronous operations
- To enable inheritance and method sharing
- To restrict access to certain properties
The prototype chain in JavaScript is crucial for inheritance. When an object is created, it inherits properties and methods from its prototype. This chain allows objects to share functionality and promotes code reusability.
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.
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.
What is tail call optimization in recursive functions and how is it handled in ES6?
- Tail call optimization is a technique where the JavaScript engine optimizes recursive functions to avoid stack overflow errors. In ES6, tail call optimization is not explicitly mandated, but certain engine implementations may provide it.
- Tail call optimization in ES6 can be achieved through the use of proper coding practices, such as making the recursive call the last operation in the function and ensuring no additional processing is performed after the recursive call.
- ES6 introduces the concept of proper tail calls (PTC), allowing some recursive functions to be optimized for tail calls. This optimization is not universally supported across all JavaScript engines.
- Tail call optimization is automatically applied to all recursive functions in ES6, ensuring that stack overflow errors are mitigated, and the recursive calls are optimized for better performance.
Proper tail calls in ES6 involve making the recursive call the last operation in a function. While not all recursive calls benefit from tail call optimization, adhering to PTC principles can enhance performance in situations where tail call optimization is applied.
________ tools are crucial in analyzing and removing unused code through tree shaking.
- Babel
- Linter
- Bundler
- Minifier
Bundlers play a key role in tree shaking. They are responsible for analyzing the dependencies between modules, identifying unused code, and removing it during the build process. Common bundlers like Webpack and Rollup are often configured to perform tree shaking to optimize the final bundle size.
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.