Popular JavaScript Interview Questions

Basic Questions

• What is JavaScript
• Is JavaScript a multithreaded language? A
• Is JavaScript asynchronous and multithreaded?
• Why JavaScript?
• What is scope? A1
• Scope and Scope chain in Javascript
• What are data types in JavaScript?
• Pass By Value And Pass By Reference In JavaScript

DOM Questions

• How to select all element using class?
• What querySelector() returns?
• How to find an element in the tree?
• How to select top most parent element?
• How to select next element?
• How to remove element?
• How to add attribute?
• How to select a data attribute?
• How to set value on the data attribute?
• How to apply style on element?
• How to wait until an element exists? A R

Demandable Questions

• What is closure?
• What is hoisting?
• What is Higher Order Function?
• What is Pure Function? A
• What is Recursion?
• Where we should use Recursion?
• What is reduce function?
• What is map function?
• What is filter function?
• Difference between == and ===?
• What is the difference between call, apply and bind?
• What is the difference between map and forEach
• What is the difference between rest parameter and spread operator A1
• Difference between Promise vs Async Await A

Basic DS and Algo

• Calculate the functional arguments?
• Find the largest number?
• Return the unique numbers from the array?
• Return the duplicate numbers from the array?
• Return the count of duplicate numbers from the array?
• Find the falsy values and return them?
• compare two arrays and returns true if both are same.
• compare two objects and return true if both are same.
• return flat array from the multi dimensional zig-zag array?
• Return truthy item from the array?
• Return falsy item from the array?

Advance Questions

• What is function Curry?
• How and where we can use function curry?
• What is Debounce in JavaScript?
• What is throttling in JavaScript?
• Difference between throttling and debouncing?
• What is event capturing and how we use?
• What is event bubbling and how we use?
• What is event delegation and how we use?
• What is Event Loop?
• How event loop works?
• Is JavaScript multi-thread?
• What is temporal dead zone? A1 A2
• What is Shadow DOM?
• What is Web Component?
• What is the difference between shadow and virtual DOM?

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