javascript - scrollX 和 pageXOffset 有什么区别

Question

下面的方法一样吗？

window.scrollX  === window.pageXOffset

window.scrollY  === window.pageYOffset

如果没有区别，为什么要引入两种方法？

Answer 1

来自 MDN:

The pageXOffset property is an alias for the scrollX property:

window.pageXOffset == window.scrollX; // always true 

For cross-browser compatibility, use window.pageXOffset instead of window.scrollX. Additionally, older versions of Internet Explorer (< 9) do not support either property and must be worked around by checking other non-standard properties.

scrollY 和 pageYOffset 也是一样。

来源:https://developer.mozilla.org/en-US/docs/Web/API/Window.scrollX