JavaScript Event Handling
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Questions and Answers

What is the primary purpose of event delegation in event handling?

  • To improve the performance of the application
  • To handle events triggered by a single element
  • To reduce the number of event listeners (correct)
  • To make the code more modular and reusable

    • What happens when an event is triggered on a DOM element?

  • The event is immediately handled by the element itself
  • The event is ignored and not propagated
  • The event is captured by the nearest ancestor element
  • The event bubbles up the DOM tree and triggers the event handler (correct)

    • What is the benefit of updating DOM elements dynamically?

  • It improves the user experience by providing instant feedback (correct)
  • It makes the application more vulnerable to security threats
  • It increases the loading time of the application
  • It reduces the complexity of the code

    • What is the relationship between event handling and application state?

    <p>Event handling updates the application state</p> Signup and view all the answers

    What is the advantage of using event handling in a web application?

    <p>It provides a more interactive and engaging user experience</p> Signup and view all the answers

    The document.querySelectorAll method returns a single element that matches the specified CSS selector.

    <p>False</p> Signup and view all the answers

    The parentNode.appendChild method inserts a new node before the reference node.

    <p>False</p> Signup and view all the answers

    The element.getAttribute method sets an attribute on an element.

    <p>False</p> Signup and view all the answers

    The element.removeEventListener method adds an event listener to an element.

    <p>False</p> Signup and view all the answers

    The document.createElement method creates a new element with the specified ID.

    <p>False</p> Signup and view all the answers

    The element.getElementsByTagName method selects all elements with the specified class name.

    <p>False</p> Signup and view all the answers

    The element.addEventListener method only works for mouse events.

    <p>False</p> Signup and view all the answers

    The parentNode.removeChild method appends a child node to the parent node.

    <p>False</p> Signup and view all the answers

    Study Notes

    Element Selection

    • document.getElementById(id) is used to select an element with a specified ID
    • document.querySelector(selector) selects the first element that matches a specified CSS selector
    • document.querySelectorAll(selector) selects all elements that match a specified CSS selector
    • element.getElementsByClassName(className) selects all elements with a specified class name
    • element.getElementsByTagName(tagName) selects all elements with a specified tag name

    DOM Manipulation

    Creating Elements

    • document.createElement(tagName) creates a new element with a specified tag name

    Appending and Inserting Elements

    • parentNode.appendChild(childNode) appends a child node to a parent node
    • parentNode.insertBefore(newNode, referenceNode) inserts a new node before a reference node

    Removing Elements

    • parentNode.removeChild(childNode) removes a child node from a parent node

    Modifying Element Attributes and Properties

    • element.setAttribute(attributeName, attributeValue) sets an attribute on an element
    • element.getAttribute(attributeName) gets the value of an attribute on an element
    • element.property = value sets a property on an element (e.g. element.src = 'image.jpg')

    Event Listeners

    Types of Events

    • Mouse events (e.g. click, mouseover, mouseout)
    • Keyboard events (e.g. keydown, keyup)
    • Form events (e.g. submit, change)
    • Window events (e.g. load, resize)

    Adding Event Listeners

    • element.addEventListener(eventType, listener) adds an event listener to an element
    • element.removeEventListener(eventType, listener) removes an event listener from an element

    Event Listener Functions

    • function(event) {...} is a function that is called when an event occurs
    • event.target is the element that triggered the event
    • event.preventDefault() prevents the default action of the event from occurring

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    Quiz Team

    Description

    This quiz covers event handling and event delegation in JavaScript, including responding to user interactions and dynamically updating DOM elements.

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