当到达页面的开头或结尾时，按键会被“记住”

Question

我有一个完全水平展开的页面，可以通过按例如Space Bar 、 Page Down 、 Right Arrow 、 Home 、 End等滚动来导航。

我遇到的问题是，例如，如果您在到达页面末尾时多次按下Page Down键，那么您将需要相同数量的Page Up按下才能向后滚动。 例如，如果您多次按左箭头，然后尝试右后记 go，则在页面开头也会发生同样的情况。

我该如何解决这个问题，以便在到达页面的开头或结尾时不会“记住”按键？

---

您可以在下面运行我的代码：

 let scrollAmount = 0 const container = document.documentElement window.onload = () => { document.body.onkeydown = event => { switch (event.code) { case "Space": case "PageDown": case "ArrowRight": case "ArrowDown": { event.preventDefault() scrollAmount += window.innerWidth break } case "PageUp": case "ArrowLeft": case "ArrowUp": { event.preventDefault() scrollAmount -= window.innerWidth break } case "Home": { scrollAmount = 0 break } case "End": { scrollAmount = container.scrollWidth break } } container.scrollTo({ top: 0, left: scrollAmount, behavior: "smooth" }) } } // Reset the scrollAmount if the user scrolls back manually. window.onscroll = event => { scrollAmount = container.scrollLeft }

 * { margin: 0; padding: 0 } html { height: 100% } html, body, section { display: flex; flex-grow: 1 } section { display: grid; place-items: center; flex: 1 0 100% } section:nth-of-type(1) { background: orange } section:nth-of-type(2) { background: limeGreen } section:nth-of-type(3) { background: royalBlue } h2 { color: white }

 <section><h2>1</h2></section> <section><h2>2</h2></section> <section><h2>3</h2></section>

Answer 1

如果您在开始或结束，添加将阻止您增加scrollAmount的限制：

• 开始 - scrollAmount为 0
• End - scrollAmount等于body.scrollWidth - window.innerWidth （body的整个宽度 - 一页的宽度）

 let scrollAmount = 0 const container = document.documentElement window.onload = () => { document.body.onkeydown = event => { switch (event.code) { case "Space": case "PageDown": case "ArrowRight": case "ArrowDown": { event.preventDefault() const maxScroll = container.scrollWidth - window.innerWidth if(scrollAmount === maxScroll) return; // if at the end, return scrollAmount += window.innerWidth break } case "PageUp": case "ArrowLeft": case "ArrowUp": { event.preventDefault() if(scrollAmount === 0) return; // if at the start return scrollAmount -= window.innerWidth break } case "Home": { scrollAmount = 0 break } case "End": { scrollAmount = container.scrollWidth - window.innerWidth break } } container.scrollTo({ top: 0, left: scrollAmount, behavior: "smooth" }) } } // Reset the scrollAmount if the user scrolls back manually. window.onscroll = event => { scrollAmount = container.scrollLeft }

 * { margin: 0; padding: 0 } html { height: 100% } html, body, section { display: flex; flex-grow: 1 } section { display: grid; place-items: center; flex: 1 0 100%; } section:nth-of-type(1) { background: orange } section:nth-of-type(2) { background: limeGreen } section:nth-of-type(3) { background: royalBlue } h2 { color: white }

 <section> <h2>1</h2> </section> <section> <h2>2</h2> </section> <section> <h2>3</h2> </section>