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。)
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
一个更好的解决方案:
function getViewportSize(w) {
var w = w || window;
if(w.innerWidth != null)
return {w:w.innerWidth, h:w.innerHeight};
var d = w.document;
if (document.compatMode == "CSS1Compat") {
return {
w: d.documentElement.clientWidth,
h: d.documentElement.clientHeight
};
}
return { w: d.body.clientWidth, h: d.body.clientWidth };
}
function isViewportVisible(e) {
var box = e.getBoundingClientRect();
var height = box.height || (box.bottom - box.top);
var width = box.width || (box.right - box.left);
var viewport = getViewportSize();
if(!height || !width)
return false;
if(box.top > viewport.h || box.bottom < 0)
return false;
if(box.right < 0 || box.left > viewport.w)
return false;
return true;
}
更新:时间在流逝,我们的浏览器也是如此。这种方法不再被推荐,如果你不需要支持ie7之前的版本,你应该使用Dan的解决方案。
原来的解决方案(现已过时):
这将检查元素是否在当前视口中完全可见:
function elementInViewport(el) {
var top = el.offsetTop;
var left = el.offsetLeft;
var width = el.offsetWidth;
var height = el.offsetHeight;
while(el.offsetParent) {
el = el.offsetParent;
top += el.offsetTop;
left += el.offsetLeft;
}
return (
top >= window.pageYOffset &&
left >= window.pageXOffset &&
(top + height) <= (window.pageYOffset + window.innerHeight) &&
(left + width) <= (window.pageXOffset + window.innerWidth)
);
}
你可以简单地修改它,以确定元素的任何部分在视口中是否可见:
function elementInViewport2(el) {
var top = el.offsetTop;
var left = el.offsetLeft;
var width = el.offsetWidth;
var height = el.offsetHeight;
while(el.offsetParent) {
el = el.offsetParent;
top += el.offsetTop;
left += el.offsetLeft;
}
return (
top < (window.pageYOffset + window.innerHeight) &&
left < (window.pageXOffset + window.innerWidth) &&
(top + height) > window.pageYOffset &&
(left + width) > window.pageXOffset
);
}
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}
}
让我感到困扰的是,该功能没有以jquery为中心的版本可用。当我看到Dan的解决方案时,我发现有机会为那些喜欢用jQuery OO风格编程的人提供一些东西。它很漂亮,很时髦,对我来说很有魅力。
哒哒,哒哒,嘣
$.fn.inView = function(){
if(!this.length)
return false;
var rect = this.get(0).getBoundingClientRect();
return (
rect.top >= 0 &&
rect.left >= 0 &&
rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
rect.right <= (window.innerWidth || document.documentElement.clientWidth)
);
};
// Additional examples for other use cases
// Is true false whether an array of elements are all in view
$.fn.allInView = function(){
var all = [];
this.forEach(function(){
all.push( $(this).inView() );
});
return all.indexOf(false) === -1;
};
// Only the class elements in view
$('.some-class').filter(function(){
return $(this).inView();
});
// Only the class elements not in view
$('.some-class').filter(function(){
return !$(this).inView();
});
使用
$(window).on('scroll',function(){
if( $('footer').inView() ) {
// Do cool stuff
}
});
下面是一个函数,它告诉你一个元素在父元素的当前视口中是否可见:
function inParentViewport(el, pa) {
if (typeof jQuery === "function"){
if (el instanceof jQuery)
el = el[0];
if (pa instanceof jQuery)
pa = pa[0];
}
var e = el.getBoundingClientRect();
var p = pa.getBoundingClientRect();
return (
e.bottom >= p.top &&
e.right >= p.left &&
e.top <= p.bottom &&
e.left <= p.right
);
}