是否有一种有效的方法来判断DOM元素(在HTML文档中)当前是否可见(出现在视口中)?
(这个问题指的是Firefox。)
当前回答
作为公共服务: Dan的答案与正确的计算(元素可以>窗口，特别是在手机屏幕上)，并正确的jQuery测试，以及添加isElementPartiallyInViewport:
顺便说一下，窗户和窗户的区别。innerWidth和document.documentElement.clientWidth是clientWidth/clientHeight不包括滚动条，while窗口。innerWidth /高。
function isElementPartiallyInViewport(el)
{
// Special bonus for those using jQuery
if (typeof jQuery !== 'undefined' && el instanceof jQuery)
el = el[0];
var rect = el.getBoundingClientRect();
// DOMRect { x: 8, y: 8, width: 100, height: 100, top: 8, right: 108, bottom: 108, left: 8 }
var windowHeight = (window.innerHeight || document.documentElement.clientHeight);
var windowWidth = (window.innerWidth || document.documentElement.clientWidth);
// http://stackoverflow.com/questions/325933/determine-whether-two-date-ranges-overlap
var vertInView = (rect.top <= windowHeight) && ((rect.top + rect.height) >= 0);
var horInView = (rect.left <= windowWidth) && ((rect.left + rect.width) >= 0);
return (vertInView && horInView);
}
// http://stackoverflow.com/questions/123999/how-to-tell-if-a-dom-element-is-visible-in-the-current-viewport
function isElementInViewport (el)
{
// Special bonus for those using jQuery
if (typeof jQuery !== 'undefined' && el instanceof jQuery)
el = el[0];
var rect = el.getBoundingClientRect();
var windowHeight = (window.innerHeight || document.documentElement.clientHeight);
var windowWidth = (window.innerWidth || document.documentElement.clientWidth);
return (
(rect.left >= 0)
&& (rect.top >= 0)
&& ((rect.left + rect.width) <= windowWidth)
&& ((rect.top + rect.height) <= windowHeight)
);
}
function fnIsVis(ele)
{
var inVpFull = isElementInViewport(ele);
var inVpPartial = isElementPartiallyInViewport(ele);
console.clear();
console.log("Fully in viewport: " + inVpFull);
console.log("Partially in viewport: " + inVpPartial);
}
测试用例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="description" content="">
<meta name="author" content="">
<title>Test</title>
<!--
<script src="http://cdnjs.cloudflare.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script src="scrollMonitor.js"></script>
-->
<script type="text/javascript">
function isElementPartiallyInViewport(el)
{
// Special bonus for those using jQuery
if (typeof jQuery !== 'undefined' && el instanceof jQuery)
el = el[0];
var rect = el.getBoundingClientRect();
// DOMRect { x: 8, y: 8, width: 100, height: 100, top: 8, right: 108, bottom: 108, left: 8 }
var windowHeight = (window.innerHeight || document.documentElement.clientHeight);
var windowWidth = (window.innerWidth || document.documentElement.clientWidth);
// http://stackoverflow.com/questions/325933/determine-whether-two-date-ranges-overlap
var vertInView = (rect.top <= windowHeight) && ((rect.top + rect.height) >= 0);
var horInView = (rect.left <= windowWidth) && ((rect.left + rect.width) >= 0);
return (vertInView && horInView);
}
// http://stackoverflow.com/questions/123999/how-to-tell-if-a-dom-element-is-visible-in-the-current-viewport
function isElementInViewport (el)
{
// Special bonus for those using jQuery
if (typeof jQuery !== 'undefined' && el instanceof jQuery)
el = el[0];
var rect = el.getBoundingClientRect();
var windowHeight = (window.innerHeight || document.documentElement.clientHeight);
var windowWidth = (window.innerWidth || document.documentElement.clientWidth);
return (
(rect.left >= 0)
&& (rect.top >= 0)
&& ((rect.left + rect.width) <= windowWidth)
&& ((rect.top + rect.height) <= windowHeight)
);
}
function fnIsVis(ele)
{
var inVpFull = isElementInViewport(ele);
var inVpPartial = isElementPartiallyInViewport(ele);
console.clear();
console.log("Fully in viewport: " + inVpFull);
console.log("Partially in viewport: " + inVpPartial);
}
// var scrollLeft = (window.pageXOffset !== undefined) ? window.pageXOffset : (document.documentElement || document.body.parentNode || document.body).scrollLeft,
// var scrollTop = (window.pageYOffset !== undefined) ? window.pageYOffset : (document.documentElement || document.body.parentNode || document.body).scrollTop;
</script>
</head>
<body>
<div style="display: block; width: 2000px; height: 10000px; background-color: green;">
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<input type="button" onclick="fnIsVis(document.getElementById('myele'));" value="det" />
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<div style="background-color: crimson; display: inline-block; width: 800px; height: 500px;" ></div>
<div id="myele" onclick="fnIsVis(this);" style="display: inline-block; width: 100px; height: 100px; background-color: hotpink;">
t
</div>
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<input type="button" onclick="fnIsVis(document.getElementById('myele'));" value="det" />
</div>
<!--
<script type="text/javascript">
var element = document.getElementById("myele");
var watcher = scrollMonitor.create(element);
watcher.lock();
watcher.stateChange(function() {
console.log("state changed");
// $(element).toggleClass('fixed', this.isAboveViewport)
});
</script>
-->
</body>
</html>
其他回答
作为公共服务: Dan的答案与正确的计算(元素可以>窗口，特别是在手机屏幕上)，并正确的jQuery测试，以及添加isElementPartiallyInViewport:
顺便说一下，窗户和窗户的区别。innerWidth和document.documentElement.clientWidth是clientWidth/clientHeight不包括滚动条，while窗口。innerWidth /高。
function isElementPartiallyInViewport(el)
{
// Special bonus for those using jQuery
if (typeof jQuery !== 'undefined' && el instanceof jQuery)
el = el[0];
var rect = el.getBoundingClientRect();
// DOMRect { x: 8, y: 8, width: 100, height: 100, top: 8, right: 108, bottom: 108, left: 8 }
var windowHeight = (window.innerHeight || document.documentElement.clientHeight);
var windowWidth = (window.innerWidth || document.documentElement.clientWidth);
// http://stackoverflow.com/questions/325933/determine-whether-two-date-ranges-overlap
var vertInView = (rect.top <= windowHeight) && ((rect.top + rect.height) >= 0);
var horInView = (rect.left <= windowWidth) && ((rect.left + rect.width) >= 0);
return (vertInView && horInView);
}
// http://stackoverflow.com/questions/123999/how-to-tell-if-a-dom-element-is-visible-in-the-current-viewport
function isElementInViewport (el)
{
// Special bonus for those using jQuery
if (typeof jQuery !== 'undefined' && el instanceof jQuery)
el = el[0];
var rect = el.getBoundingClientRect();
var windowHeight = (window.innerHeight || document.documentElement.clientHeight);
var windowWidth = (window.innerWidth || document.documentElement.clientWidth);
return (
(rect.left >= 0)
&& (rect.top >= 0)
&& ((rect.left + rect.width) <= windowWidth)
&& ((rect.top + rect.height) <= windowHeight)
);
}
function fnIsVis(ele)
{
var inVpFull = isElementInViewport(ele);
var inVpPartial = isElementPartiallyInViewport(ele);
console.clear();
console.log("Fully in viewport: " + inVpFull);
console.log("Partially in viewport: " + inVpPartial);
}
测试用例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="description" content="">
<meta name="author" content="">
<title>Test</title>
<!--
<script src="http://cdnjs.cloudflare.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script src="scrollMonitor.js"></script>
-->
<script type="text/javascript">
function isElementPartiallyInViewport(el)
{
// Special bonus for those using jQuery
if (typeof jQuery !== 'undefined' && el instanceof jQuery)
el = el[0];
var rect = el.getBoundingClientRect();
// DOMRect { x: 8, y: 8, width: 100, height: 100, top: 8, right: 108, bottom: 108, left: 8 }
var windowHeight = (window.innerHeight || document.documentElement.clientHeight);
var windowWidth = (window.innerWidth || document.documentElement.clientWidth);
// http://stackoverflow.com/questions/325933/determine-whether-two-date-ranges-overlap
var vertInView = (rect.top <= windowHeight) && ((rect.top + rect.height) >= 0);
var horInView = (rect.left <= windowWidth) && ((rect.left + rect.width) >= 0);
return (vertInView && horInView);
}
// http://stackoverflow.com/questions/123999/how-to-tell-if-a-dom-element-is-visible-in-the-current-viewport
function isElementInViewport (el)
{
// Special bonus for those using jQuery
if (typeof jQuery !== 'undefined' && el instanceof jQuery)
el = el[0];
var rect = el.getBoundingClientRect();
var windowHeight = (window.innerHeight || document.documentElement.clientHeight);
var windowWidth = (window.innerWidth || document.documentElement.clientWidth);
return (
(rect.left >= 0)
&& (rect.top >= 0)
&& ((rect.left + rect.width) <= windowWidth)
&& ((rect.top + rect.height) <= windowHeight)
);
}
function fnIsVis(ele)
{
var inVpFull = isElementInViewport(ele);
var inVpPartial = isElementPartiallyInViewport(ele);
console.clear();
console.log("Fully in viewport: " + inVpFull);
console.log("Partially in viewport: " + inVpPartial);
}
// var scrollLeft = (window.pageXOffset !== undefined) ? window.pageXOffset : (document.documentElement || document.body.parentNode || document.body).scrollLeft,
// var scrollTop = (window.pageYOffset !== undefined) ? window.pageYOffset : (document.documentElement || document.body.parentNode || document.body).scrollTop;
</script>
</head>
<body>
<div style="display: block; width: 2000px; height: 10000px; background-color: green;">
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<input type="button" onclick="fnIsVis(document.getElementById('myele'));" value="det" />
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<div style="background-color: crimson; display: inline-block; width: 800px; height: 500px;" ></div>
<div id="myele" onclick="fnIsVis(this);" style="display: inline-block; width: 100px; height: 100px; background-color: hotpink;">
t
</div>
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<br /><br /><br /><br /><br /><br />
<input type="button" onclick="fnIsVis(document.getElementById('myele'));" value="det" />
</div>
<!--
<script type="text/javascript">
var element = document.getElementById("myele");
var watcher = scrollMonitor.create(element);
watcher.lock();
watcher.stateChange(function() {
console.log("state changed");
// $(element).toggleClass('fixed', this.isAboveViewport)
});
</script>
-->
</body>
</html>
这里所有的答案都是确定元素是否完全包含在视口中，而不仅仅是以某种方式可见。例如，如果在视图的底部只有图像的一半可见，这里的解决方案将失败，考虑到“外部”。
我有一个用例，我正在通过IntersectionObserver进行惰性加载，但由于弹出过程中发生的动画，我不想观察任何已经在页面加载上交叉的图像。为此，我使用了以下代码:
const bounding = el.getBoundingClientRect();
const isVisible = (0 < bounding.top && bounding.top < (window.innerHeight || document.documentElement.clientHeight)) ||
(0 < bounding.bottom && bounding.bottom < (window.innerHeight || document.documentElement.clientHeight));
这基本上是检查顶部或底部边界是否在视口中独立。另一端可能在外面，但只要一端在里面，它至少是部分“可见”的。
作为Element.getBoundingClientRect()的支持，最简单的解决方案已经变得完美:
function isInView(el) {
const box = el.getBoundingClientRect();
return box.top < window.innerHeight && box.bottom >= 0;
}
这检查元素是否至少部分在视图中(垂直维度):
function inView(element) {
var box = element.getBoundingClientRect();
return inViewBox(box);
}
function inViewBox(box) {
return ((box.bottom < 0) || (box.top > getWindowSize().h)) ? false : true;
}
function getWindowSize() {
return { w: document.body.offsetWidth || document.documentElement.offsetWidth || window.innerWidth, h: document.body.offsetHeight || document.documentElement.offsetHeight || window.innerHeight}
}
对于类似的挑战，我非常喜欢这个要点，它为scrollIntoViewIfNeeded()暴露了一个填充。
所有必要的功夫都需要回答这个问题:
var parent = this.parentNode,
parentComputedStyle = window.getComputedStyle(parent, null),
parentBorderTopWidth = parseInt(parentComputedStyle.getPropertyValue('border-top-width')),
parentBorderLeftWidth = parseInt(parentComputedStyle.getPropertyValue('border-left-width')),
overTop = this.offsetTop - parent.offsetTop < parent.scrollTop,
overBottom = (this.offsetTop - parent.offsetTop + this.clientHeight - parentBorderTopWidth) > (parent.scrollTop + parent.clientHeight),
overLeft = this.offsetLeft - parent.offsetLeft < parent.scrollLeft,
overRight = (this.offsetLeft - parent.offsetLeft + this.clientWidth - parentBorderLeftWidth) > (parent.scrollLeft + parent.clientWidth),
alignWithTop = overTop && !overBottom;
这指的是你想知道的元素，例如，overTop或overBottom -你只需要得到漂移…
推荐文章
- 给一个数字加上st, nd, rd和th(序数)后缀
- 如何以编程方式触发引导模式?
- setTimeout带引号和不带括号的区别
- 为什么我的CSS3媒体查询不能在移动设备上工作?
- 在JS的Chrome CPU配置文件中，'self'和'total'之间的差异
- 用javascript检查输入字符串中是否包含数字
- 如何使用JavaScript分割逗号分隔字符串?
- 在Javascript中~~(“双波浪号”)做什么?
- 谷歌chrome扩展::console.log()从后台页面?
- 下一个元素的CSS选择器语法是什么?
- 未捕获的SyntaxError:
- [].slice的解释。调用javascript?
- jQuery日期/时间选择器
- 我如何用CSS跨浏览器绘制垂直文本?
- 我如何预填充一个jQuery Datepicker文本框与今天的日期?
