20 Vanilla JavaScript Interview Questions and Answers

Vanilla JavaScript is a programming language that is used to create web applications and websites. It is the language that is used to create most of the popular web applications and websites that we use today. If you are applying for a position that involves JavaScript, it is likely that you will be asked questions about Vanilla JavaScript during your interview. In this article, we will review some of the most common Vanilla JavaScript interview questions and how you should answer them.

Vanilla JavaScript Interview Questions and Answers

Here are 20 commonly asked Vanilla JavaScript interview questions and answers to prepare you for your interview:

1. What is Vanilla JavaScript?

Vanilla JavaScript is a term used to describe JavaScript that is not extended or modified by any other libraries or frameworks. It is the purest form of JavaScript and can be used to create simple or complex applications.

2. Can you name some advantages of using Vanilla JavaScript?

There are several advantages to using Vanilla JavaScript, including:

– It is lightweight and fast
– It is easy to learn and use
– It is cross-platform and can be used on any web browser
– It is flexible and can be used for a variety of purposes

3. What are the disadvantages of using Vanilla JavaScript?

The disadvantages of using Vanilla JavaScript are that it is not as widely adopted as other frameworks and libraries, so there may be less community support, and it can be more difficult to find resources and documentation. Additionally, because it is not as widely used, there may be fewer people with the skills necessary to work on a Vanilla JavaScript project.

4. When would you use Vanilla JavaScript instead of a framework like React or Angular?

Vanilla JavaScript can be used for a variety of tasks, but is most commonly used for small projects or for prototyping. It can also be used for tasks that do not require a lot of interactivity, such as simple data manipulation or fetching data from an API.

5. How do you create an object in Vanilla JavaScript?

There are a few different ways to create an object in Vanilla JavaScript. One way is to use the Object() constructor. Another way is to use the create() method of the Object prototype. Finally, you can also use the literal syntax, which is {}.

6. How can you check if a variable has been initialized in Vanilla JavaScript?

There are a few ways to check if a variable has been initialized in Vanilla JavaScript. One way is to use the typeof operator. This will return “undefined” if the variable has not been initialized. Another way is to use the === operator, which will return false if the variable has not been initialized.

7. How can you identify whether a certain property exists in an object in Vanilla JavaScript?

You can use the in operator to check if a property exists in an object.

8. How do you delete a property from an existing object in Vanilla JavaScript?

You can delete a property from an existing object in Vanilla JavaScript by using the delete operator. For example, if you have an object with a property named “foo” that you want to delete, you would use the following code:

delete myObject.foo;

9. How can you copy properties from one object to another in Vanilla JavaScript?

You can use the Object.assign() method to copy properties from one object to another.

10. What does the “this” keyword refer to in Vanilla JavaScript?

The “this” keyword in Vanilla JavaScript refers to the object that is currently being processed. In other words, it refers to the object that is currently being referred to by the code that is being executed.

11. Is it possible to implement inheritance with Vanilla JavaScript? If yes, then how?

Yes, it is possible to implement inheritance in Vanilla JavaScript. The way to do this is by using the prototype property of objects. When you create a new object, you can set its prototype property to be another object. This will give the new object all of the properties and methods of the object that it is inheriting from.

12. How do you perform string interpolation or substitution in Vanilla JavaScript?

There are a few ways to perform string interpolation or substitution in Vanilla JavaScript. One way is to use the string concatenation operator (+) to concatenate variables and strings together. Another way is to use template literals, which are enclosed by backticks (`), and can interpolate variables by surrounding them with ${}.

13. Which tool can be used for debugging vanilla JavaScript code?

The Chrome Developer Tools can be used to debug vanilla JavaScript code.

14. Can you explain what event bubbling and capturing mean in the context of Vanilla JavaScript?

Event bubbling and capturing are two different ways of handling events in Vanilla JavaScript. Event bubbling means that the event will be handled by the element that it originated from, and then bubble up to the parent elements until it is handled. Event capturing means that the event will be handled by the element that it originated from, and then bubble down to the child elements until it is handled.

15. What’s the difference between Event Delegation and Event Bubbling?

Event delegation is the process of using a single event listener to handle events for multiple elements. This is done by listening for the event at a higher level in the DOM, and then determining which element the event actually occurred on. Event bubbling is the process of an event “bubbling up” through the DOM, from the element it occurred on all the way up to the top-level element.

16. How can you add new elements after an element in Vanilla JavaScript?

You can add new elements after an element in Vanilla JavaScript by using the insertBefore() method. This method takes two arguments: the new element to be added, and the existing element after which the new element will be added.

17. How can you modify HTML markup without having to re-fetch the entire DOM structure in Vanilla JavaScript?

There are a few ways to do this in Vanilla JavaScript. One way would be to use the innerHTML property to directly modify the HTML markup. Another way would be to use the createElement and appendChild methods to create new elements and add them to the DOM.

18. How would you go about fetching data from an API endpoint using Vanilla JavaScript?

To fetch data from an API endpoint using Vanilla JavaScript, you would use the XMLHttpRequest object. This object allows you to make HTTP requests from within JavaScript, which is necessary for fetching data from an API.

19. Why is it important to understand prototypes when working with Vanilla JavaScript?

Prototypes are an important part of understanding how Vanilla JavaScript works. All objects in JavaScript have a prototype, which is an object that provides the properties and methods that the object will inherit. When you create a new object, the object will inherit the properties and methods from its prototype. understanding prototypes is important for understanding how objects work in JavaScript.

20. Can you give me some examples of real-world applications that use Vanilla JavaScript?

There are many real-world applications that use Vanilla JavaScript. Some examples include:

-Web applications
-Mobile applications
-Desktop applications
-Games