JavaScript Interview Questions For Beginners

Here are a few vital javascript interview questions that help beginners to succeed in their interviews.

1. What do you know about JavaScript?

Ans: JavaScript is a scripting language required for programming both web pages and client systems. It is a programming language that is structured, object-oriented, lightweight, efficient, and is composed of first-class functions. JavaScript can change the content of webpages.

2. Mention a few differences between Java & JavaScript.

Ans: Java is a programming language, while JavaScript is a scripting language. Developers use java to create software that can run on a virtual machine, an operating system, or a browser. In comparison, JS code is intended to run only inside a browser.

3. What are the different data types in JavaScript?

Ans:

String
Function
Boolean
Object
Number
Thanks
Undefined

4. Describe the various features of JavaScript

Ans:

A light-weight translation of a programming language with specific skills that are object-oriented.

A free, cross-platform language for scripting

Supports and combines with Java as well as other backend frameworks

Designed to construct web-centered applications

5. Mention the use of the isNaN function

Ans: The isNaN function decides if a value is a number or not.

6. Name some in-built methods in Javascript.

Ans:

anchor() - Helps to create an HTML anchor to use it as a target for hypertext.

ceil() - Returns the closest number higher than or equal to the original number

concat() - Combines two strings and returns a more recent string

constructor() - Returns the function that generated the particular instance of the object.

Date() - Returns the latest date and time

7. Name the company that developed JavaScript.

Ans: The Netscape Corporation developed the JavaScript programming language.

8. What are undeclared and undefined variables in JavaScript?

Ans: The variables which are not declared and those that do not appear in a program are known undeclared variables. The variables which are declared in the program and are not assigned any value are known as undefined variables.

9. What is the use of the 'This' keyword?

Ans: ‘This’ keyword in JavaScript applies to the object to which it belongs. It has multiple values based on where it is used. It belongs to an owner object and a global object in a method.

10. Name the two primary groups of data types in JavaScript.

Ans: There are two categories of data types:

Reference type
Primitive type

11. How to create an object in JavaScript?

Ans: JavaScript is an object-oriented scripting language. It is simple to create objects in JavaScript.

var std = { name: "Suma", age: 20, id: 364};

12. What are the global variables, and how are they declared?

Ans: Variables declared outside a function or with a window object are called global variables. Generally, the var keyword is used to declare both global and local variables.

13. What is NULL in JavaScript?

Ans: If no value is assigned to a variable, it is called a null object or null value.

14. What is a === operator?

Ans: === is a fundamental equality comparison operator, which returns false for values that are not of a similar kind.

15. How to create an array in JavaScript?

Ans: Arrays are used to store different values in a single variable. In JavaScript, an array is created using the new keyword.

var car = [" Maruti", "Benz", " BMW"]
var car = new array("Maruti", "Benz", " BMW")

Conclusion

Hence, this is the list of important Javascript interview questions for beginners. We hope you can get a little closer to your dream with these questions.

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