Q761. What is the purpose of Symbol.iterator and how do you use it?
`Symbol.iterator` is a well-known symbol that specifies the default iterator for an object, making it iterable with `for...of` loops and spread operators. ```javascript /...
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Q762. How does the Intersection Observer API work?
The Intersection Observer API provides a way to asynchronously observe changes in the intersection of a target element with an ancestor element or the viewport. **Basic u...
Q763. What are async iterators and how are they different from regular iterators?
Async iterators allow you to iterate over asynchronous data sources using `for await...of` loops, where each iteration can wait for a Promise to resolve. **Regular iterat...
Q764. What is the purpose of Object.getOwnPropertyDescriptors()?
`Object.getOwnPropertyDescriptors()` returns all own property descriptors of an object, including their attributes (value, writable, enumerable, configurable, get, set). ...
Q765. How does Promise.allSettled() differ from Promise.all()?
`Promise.allSettled()` and `Promise.all()` both handle multiple promises, but they behave differently when promises are rejected. **Promise.all() - fails fast:** ```javas...
Q766. What are the performance implications of using try-catch in JavaScript?
Try-catch blocks have performance implications, especially when used in hot code paths or when exceptions are frequently thrown. **Performance impact:** ```javascript // ...
Q767. What is the AbortController API and how is it used?
The AbortController API provides a way to abort one or more asynchronous operations, particularly useful for canceling fetch requests. **Basic usage:** ```javascript cons...
Q768. How do you implement a custom error class in JavaScript?
Custom error classes allow you to create specific error types with additional properties and methods, making error handling more precise. **Basic custom error:** ```javas...
Q769. What is the difference between synchronous and asynchronous generators?
Synchronous and asynchronous generators differ in how they produce values and handle asynchronous operations. **Synchronous generator:** ```javascript function* syncGener...
Q770. What are Proxy traps and what operations can they intercept?
Proxy traps are handler methods that intercept fundamental operations on objects, allowing you to customize their behavior. **Available traps:** ```javascript const handl...