The read-only scrollY
property of the Window
interface returns the number of pixels that the document is currently scrolled vertically. This value is subpixel precise in modern browsers, meaning that it isn't necessarily a whole number. You can get the number of pixels the document is scrolled horizontally from the scrollX
property.
Syntax
var y = window.scrollY
Value
In practice, the returned value is a double-precision floating-point value indicating the number of pixels the document is currently scrolled vertically from the origin, where a positive value means the content is scrolled to upward. If the document is rendered on a subpixel-precise device, then the returned value is also subpixel-precise and may contain a decimal component. If the document isn't scrolled at all up or down, then scrollY
is 0.
If you need an integer value, you can use Math.round()
to round it off.
In more technical terms, scrollY
returns the Y coordinate of the top edge of the current viewport. If there is no viewport, the returned value is 0.
Example
// make sure and go down to the second page if (window.scrollY) { window.scroll(0, 0); // reset the scroll position to the top left of the document. } window.scrollByPages(1);
Notes
Use this property to check that the document hasn't already been scrolled when using relative scroll functions such as scrollBy()
, scrollByLines()
, or scrollByPages()
.
The pageYOffset
property is an alias for the scrollY
property:
window.pageYOffset === window.scrollY; // always true
For cross-browser compatibility, use window.pageYOffset
instead of window.scrollY
. Additionally, older versions of Internet Explorer (< 9) do not support either property and must be worked around by checking other non-standard properties. A fully compatible example:
var supportPageOffset = window.pageXOffset !== undefined; var isCSS1Compat = ((document.compatMode || "") === "CSS1Compat"); var x = supportPageOffset ? window.pageXOffset : isCSS1Compat ? document.documentElement.scrollLeft : document.body.scrollLeft; var y = supportPageOffset ? window.pageYOffset : isCSS1Compat ? document.documentElement.scrollTop : document.body.scrollTop;
Specification
Specification | Status | Comment |
---|---|---|
CSS Object Model (CSSOM) View Module The definition of 'window.scrollY' in that specification. |
Working Draft |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
scrollY | Chrome
Full support
Yes
| Edge
Full support
Yes
| Firefox
Full support
Yes
| IE
No support
No
| Opera
Full support
Yes
| Safari
Full support
Yes
| WebView Android
Full support
Yes
| Chrome Android
Full support
Yes
| Firefox Android
Full support
Yes
| Opera Android
Full support
Yes
| Safari iOS
Full support
Yes
| Samsung Internet Android
Full support
Yes
|
Subpixel precision | Chrome Full support Yes | Edge Full support Yes | Firefox Full support 55 | IE No support No | Opera Full support Yes | Safari Full support Yes | WebView Android Full support Yes | Chrome Android Full support Yes | Firefox Android Full support 55 | Opera Android ? | Safari iOS ? | Samsung Internet Android ? |
Legend
- Full support
- Full support
- No support
- No support
- Compatibility unknown
- Compatibility unknown
- Uses a non-standard name.
- Uses a non-standard name.