Question No 1: What is DOM and what is the purpose of DOM?

DOM stands for Document Object Model. It is a programming interface for web documents that provides a way to interact with the content and structure of an HTML, document as object.

The purpose of the DOM is to provide a structured representation of a web document that can be accessed and manipulated using programming languages such as JavaScript. The DOM represents the document as a tree-like structure of objects, each object representing a specific part of the document, such as an element, attribute, or text node.

Question No 2: How will you select HTML elements using DOM? Name the DOM methods.

To select HTML elements using the DOM, several methods are available. Here are some commonly used DOM methods for selecting HTML elements:

1. getElementById()
2. getElementsByTagName()
3. getElementsByClassName()
4. querySelector()
5. querySelectorAll()

Question No 3: What is event bubble?

An event bubble is a type of DOM event propagation document object. This is one way that events are handled in the browser. Events are actions performed by the user such as clicking a button, changing a field, etc. Event handlers are used to execute code when a specific type of user interface event occurs, such as when a button is clicked or when a webpage is loaded.

Question No 4: What is a callback function and why will you use it?

A callback function is a function that is passed as an argument to another function and is executed when that function completes its work. A callback function is typically used to provide a way for a function to return a result or perform some action after an asynchronous operation has completed.

Callbacks are commonly used in JavaScript to handle asynchronous operations, such as when making an AJAX request or using setTimeout() or setInterval() to run code at a specified interval. By providing a callback function as an argument to these functions, the program can continue executing other code during the operation and then execute the callback function when the operation completes.