30+ Tricky JavaScript Interview Questions

Hi, Javascript Web Developers! In This Blog Post, We Will See 30+ Tricky Javascript Interview Questions That You Might Be Asked During The Interview As A Javascript Web Developer.

All The Questions That We Are Going To See Cover A Wide Range Of Concepts That You Should Know To Be A Better Javascript Web Developer. Whether You Are A Beginner Or Intermediate This Post Will Help You To Level Up Your Javascript Skills.

Understanding The Concepts Behind These Tricky Questions Will Boost Your Confidence And Improve Your Problem-solving Skills With JavaScript.

30+ Tricky JavaScript Interview Questions

Tricky JavaScript Questions On Basic Concepts

• What are the different data types in JavaScript?
• Explain the difference between null and undefined.
• What is the difference between == and === operators?
• How can you check if a variable is an array in JavaScript?
• What is the use of the typeof operator?
• What is the difference between let and var in terms of scope and hoisting?
• How do you clone an object in JavaScript?
• What are template literals and how do they differ from regular strings?
• Explain the difference between slice(), splice(), and split() methods.
• What is the purpose of the hasOwnProperty method?
• What are the falsy values in JavaScript?
• How do you convert a string to a number in JavaScript?
• What is the difference between Object.is() and ===?
• Explain the concept of implicit type coercion in JavaScript.
• What is the purpose of the delete operator in JavaScript?

Tricky JavaScript Questions On Funtions

• What is a higher-order function in JavaScript?Explain the difference between function declarations and function expressions.
• How can you create a closure in JavaScript?
• What is the purpose of the apply() and call() methods?
• How can you implement currying in JavaScript?
• What is the difference between bind(), call(), and apply() methods?
• How can you create a self-invoking function in JavaScript?
• What is an IIFE (Immediately Invoked Function Expression), and why would you use one?
• How can you implement function overloading in JavaScript?
• How do you implement a function that can be called both as a regular function and as a constructor?
• What is the difference between .bind() and creating a function with a different this context?
• How do you create a function that accepts a variable number of arguments?
• What is the difference between a named function and an anonymous function?
• How do you create a pure function in JavaScript?

Tricky JavaScript Questions On Scope And Hoisting

• What is the difference between var, let, and const?
• Explain lexical (static) scoping in JavaScript.
• How does hoisting work in JavaScript?
• What is the Temporal Dead Zone in JavaScript?
• How do closures work in JavaScript?
• What is the difference between global scope and local scope in JavaScript?
• How can you avoid polluting the global namespace in JavaScript?
• What is the difference between function scope and block scope?
• How does variable shadowing work in JavaScript?
• What are the implications of declaring variables without var, let, or const?
• What is the difference between a lexical environment and an execution context?
• How do function declarations and function expressions differ in terms of hoisting?
• Explain the concept of scope chain in JavaScript.
• What are the implications of using let and const in loops?
• How does hoisting affect the let and const keywords?

Tricky JavaScript Questions On Objects And Prototypes

• What is the difference between a prototype and a __proto__ property?
• How can you create an object in JavaScript?
• What is prototypal inheritance?
• How do you create a method that is shared among all instances of an object?
• Explain the difference between Object.create() and the new keyword.
• What is the difference between classical inheritance and prototypal inheritance?
• How can you check if an object is an instance of a specific constructor?
• What is a mixin, and how can you implement one in JavaScript?How do you create a deep copy of an object in JavaScript?
• What is the purpose of the Object.freeze() method?
• How do you check if an object is empty in JavaScript?
• What is the Object.getPrototypeOf() method, and how is it used?
• How can you implement multiple inheritance in JavaScript?
• What is the __proto__ property, and how is it different from prototype?
• How do you prevent the modification of an object’s properties?

Tricky JavaScript Questions On Asynchronous JavaScript

• What is the difference between synchronous and asynchronous code in JavaScript?
• How do Promises work in JavaScript?What is the purpose of async and await in JavaScript?
• How does the event loop work in JavaScript?
• What is the purpose of the then() method in Promises?
• How does the Promise.all() method work?
• What is the purpose of the Promise.race() method?
• How can you handle multiple asynchronous operations sequentially?
• What are microtasks and macrotasks in JavaScript, and how do they differ?
• How can you cancel a fetch request in JavaScript?
• What is the purpose of the Promise.allSettled() method?
• How can you handle multiple asynchronous operations with different outcomes?
• What is the AbortController API, and how do you use it?
• Explain the concept of microtasks and macrotasks in the event loop.
• How can you retry a failed promise in JavaScript?

Tricky JavaScript Questions On ES6

• What are the new features introduced in ES6?
• How do you use template literals in JavaScript?
• What is destructuring assignment, and how is it used?
• Explain the concept of arrow functions in JavaScript.
• What are JavaScript modules, and how do you use them?
• What are the benefits of using the spread operator (...)?
• How do default parameters work in ES6?
• What is the purpose of the Symbol type in ES6?
• How can you use the rest parameter syntax in functions?
• What are template strings, and how do you use them for multiline strings?
• How do you use the Map and Set objects in JavaScript?
• What are the benefits of using the WeakMap and WeakSet objects?
• How do you use the Object.entries() and Object.values() methods?
• What is the purpose of the Reflect API in JavaScript?
• How do you create and use iterators in JavaScript?

Tricky JavaScript Questions On DOM Manipulation

• How do you select elements in the DOM using JavaScript?
• What is the difference between innerHTML and textContent?
• How do you create and append an element to the DOM?
• What is event delegation, and how does it work?
• How can you handle events in JavaScript?
• How do you add or remove a class from an element using JavaScript?
• What is the difference between addEventListener and inline event handlers?
• How can you traverse the DOM using JavaScript?
• How do you handle events for dynamically added elements?
• What is the difference between stopPropagation and preventDefault?
• What is the difference between getElementById and querySelector?
• How do you handle CSS transitions and animations using JavaScript?
• What is the dataset property, and how is it used in DOM manipulation?
• How do you clone a DOM element in JavaScript?
• What is the purpose of the MutationObserver API?

Tricky JavaScript Questions On Error Handling

• What is the purpose of the try...catch statement in JavaScript?
• How do you create a custom error in JavaScript?
• What is the finally block, and when is it executed?
• How do you handle asynchronous errors in JavaScript?
• What is the purpose of the throw statement in JavaScript?
• How can you use try...catch for asynchronous code?
• What is the Error object in JavaScript, and how do you use it?
• How do you rethrow an error in a catch block?
• What are the different types of errors in JavaScript?
• How can you implement global error handling in JavaScript?
• How do you use the finally block in error handling?
• What are custom error classes, and how do you create them?
• How can you catch synchronous and asynchronous errors in a unified way?
• What is the difference between a runtime error and a logical error?
• How do you handle errors in event listeners?

Tricky JavaScript Questions On Advanced Topics

• What is memoization, and how can you implement it in JavaScript?
• Explain the concept of debouncing and throttling in JavaScript.
• How can you deep clone an object in JavaScript?
• What is the this keyword, and how does it work?
• How do you implement method chaining in JavaScript?
• What is the difference between deep cloning and shallow cloning?
• How can you debounce a function in JavaScript?
• What is the Reflect API, and how is it used?
• Explain the concept of proxies in JavaScript.
• How can you create a singleton pattern in JavaScript?
• What is the this keyword, and how does its value get determined?
• How do you implement inheritance using the class syntax in JavaScript?
• What is the purpose of the Symbol.iterator property?
• How can you create an observable object in JavaScript?
• What is the difference between an iterable and an iterator?

Tricky JavaScript Questions On Performace

• How can you improve the performance of a JavaScript application?
• What is the purpose of requestAnimationFrame()?
• How do you optimize DOM manipulation?
• What is the purpose of web workers in JavaScript?
• How can you reduce memory leaks in JavaScript?
• What is a memory leak in JavaScript, and how can you prevent it?
• How can you measure the performance of a JavaScript function?
• What are some best practices for optimizing JavaScript code?
• How can you use the Performance API in JavaScript?
• What is the purpose of lazy loading in JavaScript?
• What is the purpose of the requestIdleCallback() method?
• How do you optimize the rendering performance of a web application?
• What are some common performance bottlenecks in JavaScript applications?
• How do you use the performance.now() method?
• What are the advantages and disadvantages of using inline scripts and styles?

Tricky JavaScript Questions On Regular Expressions

• How do you create a regular expression in JavaScript?
• What is the purpose of the test() method in regular expressions?
• How do you use capturing groups in regular expressions?
• Explain the difference between exec() and match() methods.How do you perform a global search and replace using regular expressions?
• How can you use regular expressions to validate an email address in JavaScript?
• What are greedy and lazy matching in regular expressions?
• How do you escape special characters in a regular expression?
• What is the purpose of the replace() method in regular expressions?
• How can you perform a case-insensitive search using regular expressions?
• How do you use lookaheads and lookbehinds in regular expressions?
• What is the difference between [^abc] and (?!abc) in regular expressions?
• How can you create a regex to match a specific pattern in a string?
• What is the purpose of the RegExp constructor in JavaScript?
• How do you use regular expressions to extract data from a string?

Tricky JavaScript Questions On Advanced Function

• What is a generator function, and how is it used?
• How can you use the spread operator with functions?
• What is function composition, and how can you implement it?
• Explain the concept of the IIFE (Immediately Invoked Function Expression).
• How do you implement partial application in JavaScript?
• How do you use the arguments object in JavaScript functions?
• What is function composition, and how can you implement it?
• How can you memoize a function in JavaScript?What is the Function constructor, and how is it used?How can you implement a recursive function in JavaScript?
• How do you create a function that memoizes its results?
• What is the purpose of the Function.prototype.toString() method?
• How can you create a function that delays its execution using setTimeout?
• What is the purpose of the Function.prototype.apply() method?
• How do you use the Function.prototype.bind() method to create a partially applied function?

About Author