Assignment Questions with Answer.

What is the difference between getElementById, getElementsByClassName, and querySelector / querySelectorAll?

getElementById: Returns a single element with the specified ID (unique). getElementsByClassName: Returns a live HTMLCollection of elements with the specified class name. querySelector: Returns the first element that matches a CSS selector. querySelectorAll: Returns a static NodeList of all elements matching a CSS selector.

How do you create and insert a new element into the DOM?

Use document.createElement() to create the element, then appendChild() or insertBefore() to insert it into the DOM.

What is Event Bubbling and how does it work?

Event Bubbling is a process where an event starts from the target element and bubbles up to its parent elements in the DOM hierarchy.

What is Event Delegation in JavaScript? Why is it useful?

Event Delegation is a technique where a single event listener is added to a parent element to handle events from its child elements. It’s useful for improving performance and handling dynamically added elements.

What is the difference between preventDefault() and stopPropagation() methods?

preventDefault() stops the browser’s default behavior for an event. stopPropagation() prevents the event from bubbling up to parent elements.