Podcast
Questions and Answers
What does the preventDefault()
method do?
What does the preventDefault()
method do?
The preventDefault()
method can be invoked on any JavaScript object.
The preventDefault()
method can be invoked on any JavaScript object.
False
Why is it important to include a page in the href attribute even when using JavaScript?
Why is it important to include a page in the href attribute even when using JavaScript?
For accessibility reasons.
The method _____ can be used to prevent the default action of a click event.
The method _____ can be used to prevent the default action of a click event.
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Match the following events with their default behaviors:
Match the following events with their default behaviors:
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What does e.target represent in an event?
What does e.target represent in an event?
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E.currentTarget refers to the element that originated the event.
E.currentTarget refers to the element that originated the event.
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What function is called when the anchor element is clicked in the provided code?
What function is called when the anchor element is clicked in the provided code?
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In the event handler, e.preventDefault() is used to prevent the ______ action.
In the event handler, e.preventDefault() is used to prevent the ______ action.
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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What is the recommended method to bind events to an element?
What is the recommended method to bind events to an element?
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It is acceptable to hard-code all lost events in a project.
It is acceptable to hard-code all lost events in a project.
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What should you do to initiate event binding after the DOM has loaded?
What should you do to initiate event binding after the DOM has loaded?
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When binding an event, it is essential to know what type of event is being __________.
When binding an event, it is essential to know what type of event is being __________.
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Match the following event questions to their purpose:
Match the following event questions to their purpose:
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Which element is used to trigger an event in the example?
Which element is used to trigger an event in the example?
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Event delegation is a good practice when handling events in JavaScript.
Event delegation is a good practice when handling events in JavaScript.
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What is the first step in the two-step process after the DOM has loaded?
What is the first step in the two-step process after the DOM has loaded?
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Which of the following methods can be used to access data attributes in JavaScript?
Which of the following methods can be used to access data attributes in JavaScript?
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An arrow function can only be used when a function does not require any parameters.
An arrow function can only be used when a function does not require any parameters.
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What is the purpose of the 'dataset' property in JavaScript?
What is the purpose of the 'dataset' property in JavaScript?
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In JavaScript, an anonymous function can be written as _____(a) => a + 100;
In JavaScript, an anonymous function can be written as _____(a) => a + 100;
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Match the following JavaScript function types with their descriptions:
Match the following JavaScript function types with their descriptions:
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When should you preferably use a named function?
When should you preferably use a named function?
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The following is an example of a valid anonymous function: function showMessage(e) {}
The following is an example of a valid anonymous function: function showMessage(e) {}
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How do you add a click event listener to a button element in JavaScript?
How do you add a click event listener to a button element in JavaScript?
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What happens when stopImmediatePropagation() is called during an event?
What happens when stopImmediatePropagation() is called during an event?
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Event capturing fires on the innermost element first.
Event capturing fires on the innermost element first.
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What parameter must be added to the addEventListener() method to enable event capturing?
What parameter must be added to the addEventListener() method to enable event capturing?
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In event capturing, the event propagates from the ______ to the child.
In event capturing, the event propagates from the ______ to the child.
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Match the method with its function:
Match the method with its function:
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What is a key consideration when implementing event capturing?
What is a key consideration when implementing event capturing?
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Listeners of the same type can fire on parent elements when stopPropagation() is called.
Listeners of the same type can fire on parent elements when stopPropagation() is called.
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Describe a potential downside of using event capturing indiscriminately.
Describe a potential downside of using event capturing indiscriminately.
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Which type of function is recommended for reuse and legibility in most cases?
Which type of function is recommended for reuse and legibility in most cases?
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Arrow functions can be used when the name of the function is deemed unnecessary.
Arrow functions can be used when the name of the function is deemed unnecessary.
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When would you prefer using the close method in DOM manipulation?
When would you prefer using the close method in DOM manipulation?
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You can dynamically add items to a list using the event object property, ___ .
You can dynamically add items to a list using the event object property, ___ .
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What is the key takeaway for deciding when to use a named versus an anonymous function?
What is the key takeaway for deciding when to use a named versus an anonymous function?
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Using the parentNode property is favored over the closest function for DOM traversal.
Using the parentNode property is favored over the closest function for DOM traversal.
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What does the closest function do?
What does the closest function do?
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Study Notes
Event Bubbling
- Event bubbling is a propagation method where an event, triggered on an inner element, successively moves up the DOM tree to its parent elements.
- This propagates to all ancestors until the root element.
Event Capturing
- Event capturing is the opposite of bubbling.
- Events start at the parent and move down successively through the child elements until the innermost element.
- It's useful when needing to handle events on multiple nested elements in a specific order.
Stop Propagation
- Prevents further propagation of the current event throughout the DOM tree.
- It doesn't prevent default behaviors from occuring.
Stop Immediate Propagation
- Prevents further propagation of the event to other listeners on the same element, even along any ancestral line.
Event Object
- Every event handler automatically receives an event object.
- This object holds relevant information such as the event's origin, its parent, and coordinates.
PreventDefault()
- This method helps stop the default behavior of an HTML element.
- It's crucial for handling events that would otherwise cause unwanted defaults, like page reloads or form submissions.
DOM Element Selection
-
document.querySelector()
selects only the first matching element. -
document.querySelectorAll()
returns all elements matching a given selector.
Dynamic Data and Event Handlers
- Dynamically added elements will not have associated event handlers anymore.
- Event delegation is the solution to this problem.
Event Delegation
- Event delegation is a technique where event handlers are attached to a parent element rather than to individual child elements, so it can handle events that are triggered on new elements, ensuring they continue to be handled correctly.
Static vs Dynamic Data
- Static data is predefined HTML content.
- Dynamic data is updated or inserted based on external information, for example through an API.
Iterations with JavaScript
- JavaScript offers several built-in functions that iterate over arrays. Using a forEach() , or for...of loop is preferred over a simple for loop.
Function Reusability
- Functions improve code reusability by enabling the same block of code to be executed at various points.
Function Call
- Calling a function starts its execution.
- The values written within the function body modify the arguments to the function.
Function Parameters
- Values passed to functions are called parameters or arguments.
- Modifying variable values within a function won't modify the original variables outside the function.
Event Handling
-
e.preventDefault()
method stops the default behavior of an event. - This is ideal when you want to prevent a default action—such as a page reload—associated with a specific event, like a form submission or a link click, without interfering with other handlers.
Event Properties
-
e.target
retrieves the exact element that triggered the event and thee.currentTarget
is the element the event listener is tied to.
DOM Scripting
- DOM scripting is the use of JavaScript to modify or access HTML elements.
HTML Data Attributes
- HTML data attributes are used to store custom data linked to HTML elements.
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Description
Test your knowledge on JavaScript event handling and methods like preventDefault(). This quiz covers essential concepts such as event binding, default behaviors, and key event properties. Perfect for those looking to deepen their understanding of JavaScript interactions.