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Element.scrollTop

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since 2015年7月.

Element.scrollTop 屬性可以設置和獲取元素被向上捲動的高度(pixels). 元素的scrollTop 是元素頂端和能被看見的最頂端之間的距離. 當元素並未產生滾動條, 那麼scrollTop 的值預設為0.

表達式

// 獲得已經被滾動的距離(pixels)var intElemScrollTop = someElement.scrollTop;

intElemScrollTop 為element已經被滾動的距離(pixels ).

// 設置已經被滾動的距離(pixels)element.scrollTop = intValue;

scrollTop 可以被設置為任何和正整數, 注意事項:

如果元素不能滾動,scrollTop 被設置為0.
如果設置的值小於0,scrollTop 被設置為0.
如果設置的值大於內容可以被滾動的距離,scrollTop 被設置為最大值.

範例

Scrolling an element

In this example, try scrolling the inner container with the dashed border, and see how the value ofscrollTop changes.

HTML

html

<div>  <div>    <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><div>scrollTop: 0</div>

CSS

css

#scroller {  overflow: scroll;  height: 150px;  width: 150px;  border: 5px dashed orange;}#output {  padding: 1rem 0;}

JavaScript

const scroller = document.querySelector("#scroller");const output = document.querySelector("#output");scroller.addEventListener("scroll", (event) => {  output.textContent = `scrollTop: ${scroller.scrollTop}`;});