Window: scrollX property

BaselineWidely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

* Some parts of this feature may have varying levels of support.

The read-onlyscrollX property of theWindow interface returns the number of pixels by which the document is currently scrolled horizontally. 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 vertically from thescrollY property.

Value

A double-precision floating-point value indicating the number of pixels by which the document is currently scrolled horizontally from the origin, where a positive value means the content is scrolled to the right (to reveal more content to the right). In more technical terms,scrollX returns the X coordinate of the left edge of the currentviewport. If the document isn't scrolled at all left or right, thenscrollX is 0. If there is no viewport, the returned value is 0. If the document is rendered on a subpixel-precise device, then the returned value is also subpixel-precise and may contain a decimal component.

Note:If you need an integer value, you can useMath.round() to round it off.

It's possible forscrollX to be negative if the document can be scrolled to the left from the initial containing block. For example, if the document is right-to-left and content grows to the left.

Safari responds to overscrolling by updatingscrollX beyond the maximum scroll position (unless the default "bounce" effect is disabled, such as by settingoverscroll-behavior tonone), while Chrome and Firefox do not.

This property is read-only. To scroll the window to a particular place, useWindow.scroll().

Examples

This example checks the current horizontal scroll position of the document. If it's greater than 400 pixels, the window is scrolled back to the beginning.

if (window.scrollX > 400) {  window.scroll(0, 0);}

Notes

ThepageXOffset property is an alias for thescrollX property. This means if you haven't re-assigned either property,window.pageXOffset === window.scrollX is always true.