<html><head><style>body { height: 7500px;}button { position: fixed;}</style></head><body><h1>Window 对象</h1><h2>scrollBy() 方法</h2><p>单击其中一个按钮（多次）可滚动文档。</p><p>Look at the scrollbar to see the effect.</p><button onclick="scrollWin(0, 50)">向下滚动</button><br><br><button onclick="scrollWin(0, -50)">向上滚动</button><br><br><script>function scrollWin(x, y) { window.scrollBy(x, y);}</script></body></html>