Test your understanding of DOM manipulation and event handling with these beginner-friendly multiple-choice questions. This quiz covers concepts such as selecting elements, updating content, handling browser events, and interacting with web page structures.
What does 'DOM' stand for when referring to web development?
Explanation: DOM stands for Document Object Model, which represents the structured layout of a webpage as objects. The other options, such as Data Ordering Method, Display Output Mechanism, and Direct Object Mapping, are incorrect and do not refer to the structure used in web development for interacting with documents. The DOM allows scripts to dynamically access and update content, structure, and styles.
Which method selects an element with the id of 'main' in the DOM?
Explanation: getElementById('main') selects a DOM element by its unique id 'main'. selectElement and findById are not standard DOM methods, and getElementsByName is used for selecting elements by their name attribute, not id. Using the correct method ensures you interact with the intended element.
How can you change the visible text of an element to 'Hello World'?
Explanation: You use element.textContent = 'Hello World'; to change the visible text of an element. element.innerHTML('Hello World'); and element.setText('Hello World'); are incorrect method usages. element.value is only suitable for form fields such as text inputs, not general elements.
Which method returns all elements with the class 'box'?
Explanation: getElementsByClassName('box') retrieves a collection of all elements with the specified class. querySelector only returns the first matching element, and the other two methods are not standard DOM methods. Choosing the correct method ensures you can work with multiple elements efficiently.
How can you attach a click event handler to a button element?
Explanation: button.addEventListener('click', handlerFunction); is the standard way to attach a click event handler. button.onClick(handlerFunction); and button.setEvent are not valid methods for event handling. attachEvent is non-standard and deprecated, not widely supported in modern environments.
Which property allows you to change the background color of an element using the DOM?
Explanation: element.style.backgroundColor lets you modify the background color property directly. element.css.backgroundColor and element.background are not valid properties, while element.bgColor is outdated and rarely used. The style property gives access to inline styles.
To detect a key being pressed while an input is focused, which event should you handle?
Explanation: The 'keydown' event fires when any key is pressed. 'presskey' and 'keyupkey' are not valid event names, and 'keyinput' does not exist in the standard event model. 'keyup' exists but occurs after the key is released, not when it is first pressed.
Which method stops a form’s default submission when a button is clicked?
Explanation: event.preventDefault(); is the standard way to stop the default behavior, such as a form submission. event.stopDefault();, event.cancelSubmit();, and event.preventSubmission(); are not real methods and will not work. Preventing default actions is vital for custom form handling.
How do you get the value entered in a text input element?
Explanation: input.value retrieves the current value entered by the user. input.text and input.content are not standard properties for input elements. input.getValue() is also not a valid method in this context. Accessing the value property is essential for working with input data.
Which method will permanently detach an element from the DOM?
Explanation: element.remove() permanently removes the element from the DOM tree. element.hide() only changes visibility, not removal. element.delete() is not a standard DOM method, and element.detatch() is a misspelling with no effect. Proper removal is necessary to manage dynamic content.
Why would you use event delegation in a list of items?
Explanation: Event delegation lets you manage events for many elements, including those added in the future, by listening on a parent element. The other options confuse the purpose—delegation does not delay events, select specific items, or manage events for already removed elements. Event delegation simplifies and optimizes event management.
Which method creates a new DOM element, such as a 'div'?
Explanation: document.createElement('div') creates a new div element in the DOM. element.build('div'), makeElement, and createNode are not standard methods for this task. Creating elements is the first step before adding them to the document.
Which event triggers when the mouse pointer enters an element’s area?
Explanation: 'mouseover' fires when the cursor enters an element. 'mouseentering' and 'onhover' are not valid event names. 'pointerleave' triggers when the pointer leaves, not enters, an element. Monitoring mouse events is vital for interactive user experience.
What does document.getElementById('demo') return if no element has the id 'demo'?
Explanation: When no matching element exists, getElementById returns null. It does not return undefined, false, or 0. Being able to handle null values helps avoid errors when dynamically referencing elements.
Which property allows you to add or remove a CSS class from an element?
Explanation: element.classList provides methods for adding, removing, or toggling classes. element.styleClass, element.classes, and element.cssClasses are not standard DOM properties. ClassList makes managing CSS classes straightforward and reliable.
How do you add a new child element at the end of a parent element’s child list?
Explanation: parent.appendChild(child) appends the child element to the end of the parent's children. insertNode, addLast, and pushChild are not standard methods for this operation. Appending is commonly used for building and updating the DOM structure.