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Top 90+ JavaScript Interview Questions and Answers for 2023

Top 90+ JavaScript Interview Questions and Answers for 2023
JavaScript: Important Interview Questions
Top 90+ javascript questions handpicked by us to succeed in any interview. You should go through each of this question before appearing for frontend developer interviews.
- What are falsy values in JavaScript?
- Data Types in Javascript
- ForEach, Map, Filter and Reduce in Javascript
- What is Prototypal inheritance in javascript?
- What is Generator Function in Javascript
- Caching related questions (Headers, Expiry, Types etc)
- PWA related concepts ( Service Workers, Manifest etc)
- Difference between Server Side Rendering vs Client side rendering
- Throttle & Debounce in Javascript
- What is Iterators in Javascript?
- Pollyfills for in built methods(Array methods, Call, bind, apply, promise etc)
- Difference between Split, Replace, Splice, Slice?
- Query Selector in Javascript
- String related methods in javascript (substring, trim etc)
- Datatypes and Typeof related output questions in javascript
- HTML5 new features(Semantic elements)
- What is Web worker in Javascript and how it works?
- What is This in Javascript?
- What is Closure in javascript?
- Memoization in javascript
- Hoisting in javascript?
- What is Design Patterns and its uses in Javascript( Modular, Factory, Observer, Pub Sub, Singleton etc)
- Currying in javascript and related questions?
- What is Call, Apply, Bind in Javascript?
- What is Prototype Chain in Javascript?
- Declaring and extending classes using functions in Javascript(Difference between ES6 and ES5)
- What is Promises in javascript?
- What is arrow functions in Javascript?
- What is ES6 and it's features;
- Anonymous function in Javascript?
- How to flatten a nested array in Javascript?
- How to declare private variable in Javascript?
- Destructing of objects in Javascript.
- How Async and defer works in script tag?
- Difference between rest operator and spread operator?
- How Fetch() works in Javascript?
- Single page application architecture
- SEO related concepts
- What is XHR requests and how it's works?
- How Javascript works under the hood?
- Message Queue in JS
- Job Queue in JS
- Call Stack in JS
- event loop and JS Engine
- Decimal to Hexadecimal conversions
- Why do we use “use strict” in javascript?
- What is pure function in Javascript?
- let, var and const in javascript
- What is IIFE?
- Data-ng attributes
- Dom tree implementation and traversal?
- What is reactive programming?
- React based javascript interview questions
- Virtual DOM Implementation of React
- Hooks – Usestate, useeffect, useref, useCallback, useMemo
- Pure Components in React
- Higher Order Components in React
- Styled Components in React
- Context API in React
- Redux based javascript interview questions
- How redux works and Design Pattern behind redux?
- What is Shadow DOM?
- Frameworks specific questions based on your resume and previous experience.
- What is Event propagation, capturing, bubbling ?
- Event listner in javascript and how it work?
- Web Storage in javascript
- How to access nested objects and listing all key value pairs in javascript?
- Load balancers working
- How to scale applications?
- How does CDN works?
- Implementation of linked lists in javascript?
- All ES6 features
- JSON parse, stringify etc
- How does webpack works(dependency graph, chunk formation etc)?
- How does babel works?
- Node JS based basic javascript interview questions
- Deprecated react lifecycles and their drawbacks?
- Optimization of the problems that you are going to solve?
- Frameworks vs VanillaJS, advantages and disadvantages?
- What is Promises in javascript?
- How to create Deep vs Shallow Copy in Javascript?
- Binary Search related questions in javascript.
- How to delete Object Keys in javascript?
- HasOwnProperty in Javascript Objects
- Two way binding implementation in javascript.
- Binding and it's types(Implicit/Hard/Explicit/New)
- Callback vs Promise in javascript
- What is callback hell?
- Async/Await over Promise
- Eval Function in JS
- Javascript Object methods (isExtensible, freeze, sealed)
- What is the use of setTimeout, setInterval and related output question?
- Output based tricky questions based on javascript concepts
- What is the purpose of void 0?
- How to create table using object oriented javascript
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