Window：visualViewport 属性
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since 2021年8月.
Window 接口的 visualViewport 只读属性返回一个 VisualViewport 对象，表示给定窗口的可视视口。如果当前文档未完全激活，则返回 null。