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.
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All the best 👍👍
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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