Top 10 Javascript Interview Questions With Answers 👇👇
1. What is JavaScript?
JavaScript is a high-level, interpreted programming language that is used to make web pages interactive and dynamic. It is commonly used for front-end development and can also be used for back-end development with the help of Node.js.
2. What are the data types in JavaScript?
JavaScript has six primitive data types: string, number, boolean, null, undefined, and symbol. It also has an object data type, which includes arrays and functions.
3. What is the difference between == and === in JavaScript?
The == operator compares the values of two variables, while the === operator compares both the values and the types of the variables. For example, 5 == "5" would return true, but 5 === "5" would return false.
4. What is a closure in JavaScript?
A closure is a function that has access to its own scope, the outer function's scope, and the global scope. It allows for encapsulation and private data in JavaScript.
5. What is the use of the 'this' keyword in JavaScript?
The 'this' keyword refers to the object that is currently executing the current function. Its value is determined by how a function is called.
6. What are callbacks in JavaScript?
A callback is a function that is passed as an argument to another function and is executed after a specific event or task has been completed. Callbacks are commonly used in asynchronous programming.
7. What are arrow functions in JavaScript?
Arrow functions are a more concise way to write function expressions in JavaScript. They have a shorter syntax and do not bind their own 'this' value.
8. What is event bubbling in JavaScript?
Event bubbling is a mechanism in which an event triggered on a child element will also trigger on its parent elements, propagating up the DOM tree.
9. What is the difference between let and var in JavaScript?
The let keyword was introduced in ES6 and is used to declare block-scoped variables, while var declares function-scoped variables. Variables declared with var are hoisted to the top of their function scope, while let variables are not.
10. How does prototypal inheritance work in JavaScript?
In JavaScript, objects can inherit properties and methods from other objects through prototype chaining. When a property or method is accessed on an object, JavaScript will look up the prototype chain to find it if it's not directly on the object itself.
You can check these resources for Coding interview Preparation
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1. What is JavaScript?
JavaScript is a high-level, interpreted programming language that is used to make web pages interactive and dynamic. It is commonly used for front-end development and can also be used for back-end development with the help of Node.js.
2. What are the data types in JavaScript?
JavaScript has six primitive data types: string, number, boolean, null, undefined, and symbol. It also has an object data type, which includes arrays and functions.
3. What is the difference between == and === in JavaScript?
The == operator compares the values of two variables, while the === operator compares both the values and the types of the variables. For example, 5 == "5" would return true, but 5 === "5" would return false.
4. What is a closure in JavaScript?
A closure is a function that has access to its own scope, the outer function's scope, and the global scope. It allows for encapsulation and private data in JavaScript.
5. What is the use of the 'this' keyword in JavaScript?
The 'this' keyword refers to the object that is currently executing the current function. Its value is determined by how a function is called.
6. What are callbacks in JavaScript?
A callback is a function that is passed as an argument to another function and is executed after a specific event or task has been completed. Callbacks are commonly used in asynchronous programming.
7. What are arrow functions in JavaScript?
Arrow functions are a more concise way to write function expressions in JavaScript. They have a shorter syntax and do not bind their own 'this' value.
8. What is event bubbling in JavaScript?
Event bubbling is a mechanism in which an event triggered on a child element will also trigger on its parent elements, propagating up the DOM tree.
9. What is the difference between let and var in JavaScript?
The let keyword was introduced in ES6 and is used to declare block-scoped variables, while var declares function-scoped variables. Variables declared with var are hoisted to the top of their function scope, while let variables are not.
10. How does prototypal inheritance work in JavaScript?
In JavaScript, objects can inherit properties and methods from other objects through prototype chaining. When a property or method is accessed on an object, JavaScript will look up the prototype chain to find it if it's not directly on the object itself.
You can check these resources for Coding interview Preparation
Credits: https://t.iss.one/free4unow_backup
All the best 👍👍
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How to learn Programming in 2025
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Stepwise Guide on becoming a software engineer 😄👇
Choose a Programming Language: Start by picking a programming language to learn. Popular choices for beginners include Python, JavaScript, or Java.
Learn the Basics: Begin with the fundamentals of programming, including variables, data types, control structures (if-else, loops), and basic algorithms.
Data Structures and Algorithms: Gain a solid understanding of data structures (arrays, linked lists, stacks, queues) and algorithms. Telegram channels like @crackingthecodinginterview can be helpful.
Online Courses and Tutorials: Take advantage of online courses and tutorials. Platforms like Coursera, edX, and Codecademy offer a wide range of programming courses. Many free resources are shared in this channel. Just search for the desired skill/course based on your interest in this channel.
Build Projects: Practical experience is key. Create small software projects to apply what you've learned. Start with simple projects and gradually work your way up to more complex ones.
Version Control (Git): Learn how to use Git for version control. It's essential for collaborative software development.
Explore Different Fields: Software development is vast. Explore different areas like web development, mobile app development, data science, or game development to find your niche.
Contribute to Open Source: Consider contributing to open-source projects. It's a great way to gain real-world experience, collaborate with others, and build a portfolio.
Build a Portfolio: Create a portfolio of your projects on platforms like GitHub or a personal website. Showcase your skills and projects to potential employers.
Internships and Job Search: Look for internships or entry-level positions to gain professional experience. Tailor your resume and cover letter to highlight your skills and projects. Many telegram channels like @getjobss or linkedin platform might be useful to find your desired job/internship.
Interview Preparation: Practice coding interviews. Use resources like LeetCode, HackerRank, or InterviewBit to improve your problem-solving skills.
Soft Skills: Develop soft skills like communication, teamwork, and time management. These are essential in a professional environment.
Continuous Learning: Technology evolves rapidly. Stay updated by reading blogs, books, and taking advanced courses to deepen your knowledge.
Build a Strong Online Presence: Engage in tech communities, write blog posts, or share your insights on platforms like LinkedIn to showcase your expertise.
Be Persistent: Landing your first job can be challenging. Keep applying, learning, and improving your skills. Don't get discouraged by rejections.
Remember that becoming a software engineer is a journey, and it may take time. Stay committed to learning and adapting to new technologies, and you'll progress in your career.
ENJOY LEARNING 👍👍
Choose a Programming Language: Start by picking a programming language to learn. Popular choices for beginners include Python, JavaScript, or Java.
Learn the Basics: Begin with the fundamentals of programming, including variables, data types, control structures (if-else, loops), and basic algorithms.
Data Structures and Algorithms: Gain a solid understanding of data structures (arrays, linked lists, stacks, queues) and algorithms. Telegram channels like @crackingthecodinginterview can be helpful.
Online Courses and Tutorials: Take advantage of online courses and tutorials. Platforms like Coursera, edX, and Codecademy offer a wide range of programming courses. Many free resources are shared in this channel. Just search for the desired skill/course based on your interest in this channel.
Build Projects: Practical experience is key. Create small software projects to apply what you've learned. Start with simple projects and gradually work your way up to more complex ones.
Version Control (Git): Learn how to use Git for version control. It's essential for collaborative software development.
Explore Different Fields: Software development is vast. Explore different areas like web development, mobile app development, data science, or game development to find your niche.
Contribute to Open Source: Consider contributing to open-source projects. It's a great way to gain real-world experience, collaborate with others, and build a portfolio.
Build a Portfolio: Create a portfolio of your projects on platforms like GitHub or a personal website. Showcase your skills and projects to potential employers.
Internships and Job Search: Look for internships or entry-level positions to gain professional experience. Tailor your resume and cover letter to highlight your skills and projects. Many telegram channels like @getjobss or linkedin platform might be useful to find your desired job/internship.
Interview Preparation: Practice coding interviews. Use resources like LeetCode, HackerRank, or InterviewBit to improve your problem-solving skills.
Soft Skills: Develop soft skills like communication, teamwork, and time management. These are essential in a professional environment.
Continuous Learning: Technology evolves rapidly. Stay updated by reading blogs, books, and taking advanced courses to deepen your knowledge.
Build a Strong Online Presence: Engage in tech communities, write blog posts, or share your insights on platforms like LinkedIn to showcase your expertise.
Be Persistent: Landing your first job can be challenging. Keep applying, learning, and improving your skills. Don't get discouraged by rejections.
Remember that becoming a software engineer is a journey, and it may take time. Stay committed to learning and adapting to new technologies, and you'll progress in your career.
ENJOY LEARNING 👍👍
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2. CSS ➝
◀️ https://css-tricks.com
3. JavaScript ➝
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8. SQL ➝
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Evolution of Programming Languages🖥️
🔰Programming Languages🔰
1. JAVA:
More than 85% android apps are created using JAVA. It is also used in big (big means big) websites. It is a portable programming language which makes it easy to use on multi platforms.
2. Java Script:
Its a browser/client side language. It makes the webpage more interactive. Like for example when you enter a comment on Facebook then the whole page doesn’t load., just that comment is added. This kind of functionalities are added into webpages with JavaScript. Javascript brought about a revolution in webapps.
3. Assembly Language:
The most low level programming language because its nothing more than machine code written in human readable form. Its hard to write and you need to have deep understanding of computers to use this because you are really talking with it. Its very fast in terms of execution.
4. C:
Its a low level language too that’s why its fast. It is used to program operating system, computer games and software which need to be fast. It is hard to write but gives you more control of your computer.
5. C++ :
Its C with more features and those features make it more complex.
6. Perl:
A language which was developed to create small scripts easily . Programming in Perl is easy and efficient but the programs are comparatively slower.
7. Python:
Perl was made better and named Python. Its easy, efficient and flexible. You can automate things with python in a go.
8. Ruby:
Its similar to Python but it became popular when they created a web application development framework named Rails which lets developers to write their web application conveniently.
9. HTML and CSS:
HTML and CSS are languages not programming languages because they are just used display things on a website. They do not do any actual processing. HTML is used to create the basic structure of the website and then CSS is used to make it look good.
10. PHP:
It is used to process things in a website. It is server-sided language as it doesn’t get executed in user browser, but on the server. It can be used to generate dynamic webpage content.
11. SQL:
This is not exactly a programming language. It is used to interact with databases.
➡️ This list could be long because there are too many programming language but I introduced you to the popular ones.
❓Which Language Should Be Your First Programming Language?
✅ Suggestions..
1. Getting Started
Learn HTML & CSS. They are easy and will give you a basic idea of how programming works. You will be able to create your own webpages. After HTML you can go with PHP and SQL, so will have a good grasp over web designing and then you can go with python, C or Java. I assure you that PHP, HTML and SQL will be definitely useful in your hacking journey.
2. Understanding Computer And Programming Better
C..The classic C! C is one of the most foundational languages. If you learn C, you will have a deep knowledge of Computers and you will have a greater understanding of programming too, that will make you a better programmer. You will spend most of your time compiling though (just trying to crack a joke).
3. Too Eager To Create Programs?
Python! Python is very easy to learn and you can create a program which does something instead of programming calculators. Well Python doesn’t start you from the basics but with if you know python, you will be able to understand other languages better. One benefit of python is that you don’t need to compile the script to run it, just write one and run it.
Join for more: https://whatsapp.com/channel/0029VahiFZQ4o7qN54LTzB17
🔰Programming Languages🔰
1. JAVA:
More than 85% android apps are created using JAVA. It is also used in big (big means big) websites. It is a portable programming language which makes it easy to use on multi platforms.
2. Java Script:
Its a browser/client side language. It makes the webpage more interactive. Like for example when you enter a comment on Facebook then the whole page doesn’t load., just that comment is added. This kind of functionalities are added into webpages with JavaScript. Javascript brought about a revolution in webapps.
3. Assembly Language:
The most low level programming language because its nothing more than machine code written in human readable form. Its hard to write and you need to have deep understanding of computers to use this because you are really talking with it. Its very fast in terms of execution.
4. C:
Its a low level language too that’s why its fast. It is used to program operating system, computer games and software which need to be fast. It is hard to write but gives you more control of your computer.
5. C++ :
Its C with more features and those features make it more complex.
6. Perl:
A language which was developed to create small scripts easily . Programming in Perl is easy and efficient but the programs are comparatively slower.
7. Python:
Perl was made better and named Python. Its easy, efficient and flexible. You can automate things with python in a go.
8. Ruby:
Its similar to Python but it became popular when they created a web application development framework named Rails which lets developers to write their web application conveniently.
9. HTML and CSS:
HTML and CSS are languages not programming languages because they are just used display things on a website. They do not do any actual processing. HTML is used to create the basic structure of the website and then CSS is used to make it look good.
10. PHP:
It is used to process things in a website. It is server-sided language as it doesn’t get executed in user browser, but on the server. It can be used to generate dynamic webpage content.
11. SQL:
This is not exactly a programming language. It is used to interact with databases.
➡️ This list could be long because there are too many programming language but I introduced you to the popular ones.
❓Which Language Should Be Your First Programming Language?
✅ Suggestions..
1. Getting Started
Learn HTML & CSS. They are easy and will give you a basic idea of how programming works. You will be able to create your own webpages. After HTML you can go with PHP and SQL, so will have a good grasp over web designing and then you can go with python, C or Java. I assure you that PHP, HTML and SQL will be definitely useful in your hacking journey.
2. Understanding Computer And Programming Better
C..The classic C! C is one of the most foundational languages. If you learn C, you will have a deep knowledge of Computers and you will have a greater understanding of programming too, that will make you a better programmer. You will spend most of your time compiling though (just trying to crack a joke).
3. Too Eager To Create Programs?
Python! Python is very easy to learn and you can create a program which does something instead of programming calculators. Well Python doesn’t start you from the basics but with if you know python, you will be able to understand other languages better. One benefit of python is that you don’t need to compile the script to run it, just write one and run it.
Join for more: https://whatsapp.com/channel/0029VahiFZQ4o7qN54LTzB17
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🔰 Learn CSS In 20 Days RoadMap
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