Most Asked 20+ JavaScript Conceptual Interview Questions

Prepare for your JavaScript interview with key questions on closures, promises, 'this' keyword, and more. Boost your confidence and ace your next coding challenge!
Total questions: 16
1. How does the "this" keyword work in JavaScript, explain with the help of examples and what are some common pitfalls to be aware of when using it?
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The "this" keyword in JavaScript refers to the object that it belongs to. It allows us to access the...
2. How does an IIFE work in JavaScript, and why would you use it? Also provide an example
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An Immediately Invoked Function Expression (IIFE) is a function that is immediately executed as s...

3. Can you explain how the event loop works in JavaScript and what it does?
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The event loop is a fundamental part of the JavaScript runtime environment that allows it to hand...

4. How do callbacks differ from other synchronous constructs like functions or loops in JavaScript, and why are they preferred in certain situations?
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Callbacks differ from other synchronous constructs like functions or loops in that they are asynchro...
5. Can you provide an explanation of callback hell in JavaScript, including some common scenarios where it may occur and possible solutions to address it?
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Callback hell refers to a programming pattern where multiple nested functions are called asynchronou...
6. What is a promise in JavaScript and how does it work?
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A promise in JavaScript is an object that represents the eventual completion (or failure) of an asyn...
7. What is the difference between Promise.all and Promise.allSettled in JavaScript?
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Promises are a fundamental part of asynchronous programming in JavaScript. They allow us to represen...
8. What is the difference between Promise.any and Promise.race in JavaScript?
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Promises are an essential part of asynchronous programming in JavaScript. They allow us to represent...
9. Can you provide an example to illustrate the differences between `proto` and `prototype` in JavaScript, including how they are used and what they do?
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In JavaScript, both `proto` and `prototype` refer to the same concept: the parent object in the prot...
10. Can you explain what the job queue or microtask queue is in JavaScript and how it works?
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A job queue is a data structure that allows multiple tasks to be processed asynchronously. In JavaSc...
11. Explain the concept of 'this' keyword in JavaScript. Also, how does it work inside of the event handlers?
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In JavaScript, the `this` keyword refers to the object that is executing the code it belongs to. It ...
12. What is Cross-Origin Resource Sharing (CORS) and how do you handle it in JavaScript?
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Cross-Origin Resource Sharing (CORS) is a security feature implemented by web browsers that restrict...
13. What is Cross-Site Scripting (XSS) and how can we prevent it?
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Cross-Site Scripting (XSS) is a common security vulnerability that allows an attacker to inject mali...
14. What are async iterators and generators in JavaScript?
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Async iterators and generators are two new features introduced in JavaScript with ES6. They provi...

15. What are dynamic imports in JavaScript?
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Dynamic imports in JavaScript allow you to load code asynchronously and on-demand, instead of inc...

16. What are the differences between the arrow functions and the regular functions in JavaScript?
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Syntax and Conciseness:

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