10 Essential JavaScript Interview Questions and Answers

JavaScript is the most misunderstood programming language. So it’s become tough when you talk about it.

So, I had face interviews about JavaScript sometimes. Now I’m going to share my experience and most essential JavaScript Interview Questions and Answers.

What is JavaScript?

JavaScript is a client-side and server-side scripting language inserted into HTML pages and is understood by web browsers. JavaScript is also an Object-based Programming language.

What are the differences between Java and JavaScript?

Java is a complete programming language. In contrast, JavaScript is a coded program that can be introduced to Html pages, These two languages are not at all interdependent and are designed for different intent. Java is an object-oriented programming or structured programming language, whereas JavaScript is a client-side scripting language.

What are JavaScript Data Types?

Following the JavaScript Data types:
* Number
* String
* Boolean
* Object
* Undefined

What are undeclared and undefined variables?

Undeclared variables are those that do not exist in programming and are not declared. If the program tries to read the value of an undeclared variable, then a runtime error is encountered.

What are global variables?

Global variables are available throughout the length of the code so that it has no scope. The var keyword is used to declare a local variable or object. If the var keyword is omitted a global variable is declared.

What is the working off times in JavaScript?

Times are used to execute a piece of code at a set time or repeat the code in a given interval. This is done by using the functions setTimeout, setInterval, and clearInterval.

What would be the result of 3+2+”7"?

Since 3 and are integers, they will be added numerically. And since 7 is a string, its concatenation will be done. So the result would be 57.

What do you mean by NULL in JavaScript?

the Null is used to represent no value or no object. It implies no object or null string, no valid boolean value no number, and no array object.

What is an undefined value in JavaScript?

Undefined values mean the variable used in the code doesn’t exist, the variable is not assigned to any value, the property does not exist.