JavaScript DOM Manipulation 2

Question 1

What does `document.querySelector()` return?

Accepted Answer

The first element matching the CSS selector

Answer

`document.querySelector()` returns the first Element within the document that matches the provided CSS selector string, or `null` if no match is found.

Question 2

What is event bubbling in the DOM?

Accepted Answer

An event that propagates from the target element up through its ancestors

Answer

Event bubbling is the process where an event triggered on a child element propagates upward through the DOM tree, triggering any registered event listeners on ancestor elements.

Question 3

How do you add a CSS class to a DOM element?

Accepted Answer

element.classList.add('myClass')

Answer

`element.classList.add('myClass')` is the modern and recommended way to add a CSS class. It preserves existing classes, unlike `element.className = 'myClass'` which replaces all classes.

Question 4

What does `event.preventDefault()` do?

Accepted Answer

Prevents the browser's default action for the event

Answer

`event.preventDefault()` tells the browser not to execute its default behavior for the event. For example, preventing a form from submitting, stopping a link from navigating, or blocking a checkbox from toggling.

Question 5

What is the difference between `innerHTML` and `textContent`?

Accepted Answer

`innerHTML` parses HTML tags; `textContent` treats content as plain text

Answer

`innerHTML` sets or gets the HTML markup inside an element, parsing HTML tags. `textContent` sets or gets the text content, treating everything as plain text (HTML tags are escaped, not rendered).

JavaScript Practice Test

JavaScript Practice Test

JavaScript DOM Manipulation 2