Computer Science
Grade 5
20 min
Mouse Hover Events: Changing Appearance
Use mouse hover events to change the appearance of an object when the mouse hovers over it.
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Introduction & Learning Objectives
Learning Objectives
Define what a 'mouse hover' event is in programming.
Explain the role of an event handler in response to a user action.
Create a program that changes an object's color when the mouse pointer moves over it.
Use a 'mouse out' event to change an object back to its original state.
Change multiple properties of an object (e.g., size and color) at the same time using a single hover event.
Debug a simple program where a hover effect is not working as expected.
Ever wonder how a button on a website seems to 'glow' or get bigger right before you click it? ✨ Let's learn the secret code that makes that magic happen!
In this lesson, you will learn how to make your computer programs react when a user moves their mouse over an...
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Key Concepts & Vocabulary
TermDefinitionExample
EventAn action that happens in a program, like a mouse click, a key press, or the mouse pointer moving onto something.When you move your mouse pointer over a 'Play' button, that's a 'mouse hover' event.
Event HandlerA special block of code that 'listens' for a specific event and tells the computer what to do when that event happens.An event handler could listen for a 'mouse hover' event on a button and its job would be to run the code that changes the button's color to green.
Mouse HoverThe specific event that happens when the user's mouse pointer enters the area of an on-screen object.Moving your mouse from the background onto a picture of a cat triggers a 'mouse hover' event on the cat picture.
Mouse...
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Core Syntax & Patterns
The 'On Mouse Hover' Pattern
WHEN object is hovered over, DO [action]
Use this pattern to make something happen the moment the mouse pointer touches an object. The action is usually changing a property, like color or size.
The 'On Mouse Out' Pattern
WHEN mouse moves off object, DO [action]
Use this pattern to reverse the change made by the 'On Mouse Hover' event. This makes the object go back to normal after the mouse leaves.
Changing Multiple Properties
WHEN object is hovered over, DO [action 1], [action 2], ...
Inside a single event handler, you can list multiple actions to perform at the same time. For example, you can make an object change color AND get bigger on hover.
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Challenging
A button has two events: `ON HOVER, set color to green`. `ON CLICK, set color to blue`. If you hover over the button (it turns green), then CLICK it (it turns blue), then move your mouse away, what should a good `ON MOUSE LEAVE` event do?
A.Set the color to green.
B.Do nothing; leave the color blue.
C.Set the color to its original, pre-hover color.
D.Set the color to a random color.
Challenging
You want an image to slowly fade into view when you hover over it, instead of just appearing instantly. What programming concept, besides an event handler, would you need to use?
A.single conditional (IF statement).
B.variable to store the user's name.
C.way to save a file.
D.timer or a loop that runs over a short period of time.
Challenging
You have a menu with 5 buttons in a row. You want ALL 5 buttons to turn red when the mouse hovers over ANY of the 5 buttons. What is the most efficient way to code this?
A.Write 25 different IF statements to check every possibility.
B.Create a separate `on mouse hover` event for each button that changes only its own color.
C.Have each button's `on mouse hover` event call a single function that turns all 5 buttons red.
D.Make the user click a separate 'Turn Red' button first.
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