Beginner, Intermediate, and Advanced Level JavaScript Interview Questions

Google and Facebook use JavaScript to create complicated and desktop-like online apps. Moreover, JS has become one of the most popular languages for developing server-side software. That is why many people want to make a career in it. I think you are already familiar with this fact. That is why you are reading this blog about JavaScript interview questions.

However, if you are also planning to make your career in it, start enhancing your skills. Also, prepare yourself for the interview for your job. To know the answers to several JS interview questions, go through this blog. You will get to know the JavaScript interview questions for freshers, intermediates, and advanced levels. So, scroll down to know the important interview questions for JavaScript to prepare yourself for the next interview. Here we go!

Note:- If you need JavaScript Assignment Help or HTML Assignment Help you can discuss your requirements with our experts anytime.

JavaScript Interview Questions For Beginners

What is JavaScript?

JavaScript is an object-oriented, lightweight, interpretive programming language. It allows you to add interactivity to other static HTML websites. Netscape, Internet Explorer, and other web browsers support the language’s general-purpose foundation.

What are the features of JavaScript?

JavaScript has the following features:

• It is an interpreted, lightweight programming language.
• JS helps in the development of network-centric applications.
• It works in combination with and supports Java.
• Also, it is a scripting language that is open and cross-platform.

Is JS a case-sensitive case?

Yes, JavaScript takes the case into account. The capitalization of letters in language keywords, variables, function names, and other identifiers must always be consistent.

What are the advantages of JS?

The advantages of using JavaScript are as follows:

Less Server Interaction

You can verify user input before sending the page to the server. However, this reduces server traffic, resulting in lower server strain.

Immediate Feedback

Visitors get immediate feedback instead of having to wait for a page reload to discover whether they have forgotten something.

Increase In Interactivity

You can make interfaces that respond when the user moves their mouse over them or activates them with the keyboard.

Enhance The user interface

You can use JavaScript to provide a rich interface for your site’s users. It creates strong drag-and-drop components and sliders.

In JavaScript, what are the scopes of variables?

The scope of a variable is the area of your program where it is set. Only two scopes are available for JavaScript variables.

Global Variables

A global variable is visible throughout your JavaScript code since it has global scope.

Local Variables

Only the function in which a local variable is visible. The arguments of a function are always unique to that function.

What is Callback?

A callback is a basic JavaScript function. It sends a method as an argument or option. A call-back function is run after another function has completed its execution. Functions are objects in JavaScript. As a result, functions can take variables from other functions and return them.

Intermediate Level for JavaScript Interview Questions

What is the difference between Attributes and Properties?

Attributes give additional information about an element. For example, its id, type, and value. Whereas, the property is the value assigned to the property. For example, type=”text,” value=”Name,” etc.

How many different ways is JS code used in an HTML file?

The following are the 3 different ways that JS code use in HTML files;

• Inline
• Internal
• External

A JavaScript inline function assigns to a variable generated at runtime. Also, it can be reused and distinguished from anonymous functions. When you require JavaScript for a function, you may either have it included in the page or stored in a separate file. An internal script differs from an external script in this way.

What are the various ways for defining variables in JavaScript?

In JavaScript, there are 3 methods to define a variable:

VAR

The JavaScript variables statement declares a variable and sets the variable’s value. Variable declarations are handled before the code is executed. For example, var a=10.

Const

The principle behind const functions is that they can not change the object. A function defined as const can be run on any object.

Let

This indicates that a variable, like a counter in a loop or a value swap in an algorithm, can be reallocated. It also indicates that the variable will only be usable in the block in which it is set.

What is the definition of a Typed language?

Values are related to values rather than variables in typed languages. There are two types:

Dynamically

The variable can have various kinds in this case. For example, in JS, a variable can hold numbers and characters.

Statically

In this case, the variable can only contain one type. For example, a string variable in Java that can only hold a collection of characters and nothing else.

What’s the difference between session storage and local storage?

Session Storage

Session storage is related to local storage. The data kept in session storage expires when the page session ends. But, data stored in local storage does not. Session storage is deleted when the browser is stopped.

Local Storage

For each HTTP request, the data is not delivered back to the server. For example, HTML, pictures, JavaScript, CSS, etc. Also, it decreases the amount of traffic between the client and the server. It will remain either clean manually through settings or an application.

Advance Level JavaScript Interview Questions

What is the ‘Strict’ mode in JavaScript, and how do I activate it?

Strict mode allows you to improve error checking in your code.

• You cannot use implicitly declared variables in strict mode. Also, you cannot give a value to a read-only property or add a property to a non-extensible object.
• Add “use strict” at the beginning of a file, program, or function to enable strict mode.

In JavaScript, what is a prompt box?

A prompt box is a box that provides a text box for the user to submit input. The prompt () function shows a dialogue box. It requests input from the visitor. A prompt box is often used if you want the user to enter a value before proceeding to the next page. After entering an input value into a prompt box, the user must click either “OK” or “Cancel” to proceed.

In JavaScript, what are escape characters?

JavaScript escape characters allow you to write special characters in your program without damaging it. When working with special characters, it is necessary. For example, single quotes, double quotes, apostrophes, and ampersands, escape characters (Backslash). To make the characters appear, add a backslash before them.

Final Words

So, we have discussed some of the JavaScript interview questions in the above blog. These questions are important for you to practice before an interview. However, I hope you find these JavaScript Interview Questions useful in your job interviews. If you have recently attended an interview, you can practice those questions too for your next interview. Furthermore, I wish you all the best in your future career.