Element: scrollTop property
The Element.scrollTop
property gets or sets the number of pixels by which an element's content is scrolled from its top edge. This value is subpixel precise in modern browsers, meaning that it isn't necessarily a whole number.
Value
A double-precision floating-point value indicating the number of pixels by which the element is currently scrolled vertically from the origin, where a positive value means the element is scrolled down (to reveal more content to the bottom). If the element isn't scrolled at all up or down, then scrollTop
is 0. If the document is not the active document, 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.
It's possible for scrollTop
to be negative if the element can be scrolled up from the initial containing block. For example, if the element's flex-direction
is column-reverse
and content grows upwards, then scrollTop
is 0
when the scrollbar is at its bottommost position (at the start of the scrolled content), and then increasingly negative as you scroll towards the end of the content.
Safari responds to overscrolling by updating scrollTop
beyond the maximum scroll position (unless the default "bounce" effect is disabled, such as by setting overscroll-behavior
to none
), while Chrome and Firefox do not. For example, scrollTop
may be negative on Safari just by continuing to scroll up when the element is already at the top.
The scrollTop
property can be set, which causes the element to scroll to the specified vertical position, in the same way as using Element.scroll()
with behavior: "auto"
.
Examples
Scrolling an element
In this example, try scrolling the container with the dashed border, and see how the value of scrollTop
changes.
HTML
<div id="container">
<p>
Far out in the uncharted backwaters of the unfashionable end of the western
spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this
at a distance of roughly ninety-two million miles is an utterly
insignificant little blue green planet whose ape-descended life forms are so
amazingly primitive that they still think digital watches are a pretty neat
idea.
</p>
</div>
<div id="output">scrollTop: 0</div>
CSS
#container {
overflow: scroll;
height: 150px;
width: 150px;
border: 5px dashed orange;
}
#output {
padding: 1rem 0;
}
JavaScript
const container = document.querySelector("#container");
const output = document.querySelector("#output");
container.addEventListener("scroll", (event) => {
output.textContent = `scrollTop: ${container.scrollTop}`;
});
Result
Specifications
Specification |
---|
CSSOM View Module # dom-element-scrolltop |
Browser compatibility
BCD tables only load in the browser