WheelEvent deltaY Property
Example
Return whether the user scrolls up or down:
function myFunction(event) {
var y = event.deltaY;
}
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Description
The deltaY property returns a positive value
when scrolling down, and a negative value when scrolling up, otherwise 0.
Note: This property is read-only.
Syntax
event.deltaY
Technical Details
| Return Value: | A Double, indicating the scrolling direction of the mouse wheel |
|---|
Related Pages
HTML DOM reference: WheelEvent deltaX Property
More Examples
Example
Scroll inside a DIV to make it bigger/smaller:
function myFunction(event) {
var y = event.deltaY;
var
currentSize = event.target.style.width;
if (y > 0) {
newSize = parseInt(currentSize) + 10;
} else {
newSize = parseInt(currentSize) - 10;
}
event.target.style.width = newSize + "px";
event.target.style.height
= newSize + "px";
}
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Browser Support
event.deltaY is a DOM Level 4 (2015) feature.
It is supported in all modern browsers:
| Chrome | Edge | Firefox | Safari | Opera |
| Yes | Yes | Yes | Yes | Yes |
event.deltaY is not supported in Internet Explorer 11 (or earlier).
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