此脚本为活动部分发出活动类。最近注意到它在小屏幕上停止工作。即使在 Chrome 的开发人员控制台中，我也会开始增加屏幕尺寸，它就会出现，一旦我开始减小它就会立即停止工作（活动类消失）。但仅适用于较长的部分，在较短的部分中一切正常。如何解决这个问题？
在代码片段中，我设置了一个较大的固定高度，因此投资组合链接不会接收活动类，在我的示例中，当部分宽度增加时，其高度会减小，因此在某些时候一切都会开始工作。
const links = document.querySelectorAll('.nav-link');
const sections = [... document.querySelectorAll('.forJS')];
const callback = (entries) => {
links.forEach((link) => link.classList.remove('active'));
const elem = entries.find((entry) => entry.isIntersecting);
if (elem) {
const index = sections.findIndex((section) => section === elem.target);
links[index].classList.add('active');
}
}
let observer = new IntersectionObserver(callback, {
rootMargin: '0px',
threshold: 0.5
});
sections.forEach((section) => observer.observe(section));section {
height: 100vh;
scroll-y: auto;
}
.long{
height: 300vh;
}
.nav-link.active{
color: red;
}<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.min.js"></script>
<link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet"/>
<body>
<header class="fixed-top">
<nav class="navbar navbar-expand-lg navCustom">
<div class="container">
<ul class="navbar-nav justify-content-center">
<li class="nav-item">
<a class="nav-link" href="#main">Main</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#about">About us</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#portfolio">Portfolio</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#contacts">Contacts</a>
</li>
</ul>
</div>
</nav>
</header>
<section class="forJS text-center">Some info 1</section>
<section class="forJS text-center">Some info 2</section>
<section class="forJS text-center long">Some info 3</section>
<section class="text-center">Some info 4</section>
<section class="text-center">Some info 5</section>
<section class="text-center">Some info 6</section>
<section class="text-center">Some info 7</section>
<section class="text-center">Some info 8</section>
<section class="text-center">Some info 9</section>
<section class="forJS text-center">Some info 10</section>
</body>threshold: 0.5为了解决这个问题，您可以将阈值调整为较小的值，例如 0.25。这将修复长部分的行为，但它会使较短部分的活动链接提前更改。因此，我建议您添加 2 个观察者：1 个用于阈值为 0.5 (
.forJS:not(.long).forJS.longconst links = document.querySelectorAll('.nav-link');
const sectionsShort = [...document.querySelectorAll('.forJS:not(.long)')];
const sectionsLong = [...document.querySelectorAll('.forJS.long')];
const sections = [...document.querySelectorAll('.forJS')];
const callback = entries => {
links.forEach((link) => link.classList.remove('active'));
const elem = entries.find((entry) => entry.isIntersecting);
if (elem) {
const index = sections.findIndex((section) => section === elem.target);
links[index].classList.add('active');
}
}
const observerShort = new IntersectionObserver(callback, {
rootMargin: '0px',
threshold: .5,
});
const observerLong = new IntersectionObserver(callback, {
rootMargin: '0px',
threshold: .25,
});
sectionsShort.forEach((section) => {
observerShort.observe(section)
});
sectionsLong.forEach((section) => {
observerLong.observe(section)
});
我遇到了同样的问题，最终根据视口和截面高度分别计算阈值。
对我来说，我使用了这个片段，它的效果就像一个魅力：
const viewportHeight = window.innerHeight;
sections.forEach((element) => {
if (typeof element === "undefined" || element === null) {
return;
}
const threshold = viewportHeight / element.clientHeight * 0.6; // element fills 60% of the viewport
observers.current[key] = new IntersectionObserver(
callback,
{threshold}
);
observers.current[key].observe(element as Element);
});
请像下面这样更改阈值，它会起作用。
const links = document.querySelectorAll('.nav-link');
const sections = [... document.querySelectorAll('.forJS')];
const callback = (entries) => {
links.forEach((link) => link.classList.remove('active'));
const elem = entries.find((entry) => entry.isIntersecting);
if (elem) {
const index = sections.findIndex((section) => section === elem.target);
links[index].classList.add('active');
}
}
let observer = new IntersectionObserver(callback, {
rootMargin: '0px',
threshold:[.5,0] // threshold changed
});
sections.forEach((section) => observer.observe(section));