Q1161. How do you implement a singleton pattern in JavaScript?
The singleton pattern ensures a class has only one instance and provides a global access point to it. **Classic singleton with closure:** ```javascript const Singleton = ...
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Q1162. What is the Performance API and how is it used for measuring performance?
The Performance API provides high-precision timing information for measuring web application performance. **Basic timing:** ```javascript // High-resolution timestamp con...
Q1163. What are the best practices for optimizing JavaScript bundle size?
Optimizing bundle size improves load times, reduces bandwidth usage, and enhances user experience, especially on slow networks. **1. Code splitting:** ```javascript // Sp...
Q1164. What is JavaScript?
JavaScript is a programming language used to create interactive and dynamic web pages, as well as to create more complex applications on the client and server side.
Q1165. What is the difference between let, const, and var in JavaScript?
The var keyword is used for variable declaration in older versions of JavaScript, while let and const were introduced in ES6. Var has a function-level scope, while let an...
Q1166. What is the scope chain in JavaScript?
The scope chain is how Javascript looks for variables. When looking for variables through the nested scope, the inner scope first looks at its own scope.
Q1167. What is a closure in JavaScript?
In JavaScript, a closure is created when a function is defined inside another function and the inner function is returned from the outer function. The inner function has ...
Q1168. What is the purpose of the "use strict" statement in JavaScript?
The "use strict" statement is used to enable strict mode in JavaScript, which helps to prevent common errors and make the code more secure. It prevents things like use of...
Q1169. What is the difference between synchronous and asynchronous code in JavaScript?
Synchronous code executes tasks in sequence and waits for each task to complete before moving on, while asynchronous code can execute multiple tasks simultaneously and do...
Q1170. What is the difference between async/await and promises in JavaScript?
Both async/await and Promises are used to handle asynchronous operations in JavaScript. However, async/await is built on top of Promises which makes asynchronous code mor...