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
/**
* Returns Element placement information in Viewport
* @link https://stackoverflow.com/a/70476497/2453148
*
* @typedef {object} ViewportInfo - Whether the element is…
* @property {boolean} isInViewport - fully or partially in the viewport
* @property {boolean} isPartiallyInViewport - partially in the viewport
* @property {boolean} isInsideViewport - fully inside viewport
* @property {boolean} isAroundViewport - completely covers the viewport
* @property {boolean} isOnEdge - intersects the edge of viewport
* @property {boolean} isOnTopEdge - intersects the top edge
* @property {boolean} isOnRightEdge - intersects the right edge
* @property {boolean} isOnBottomEdge - is intersects the bottom edge
* @property {boolean} isOnLeftEdge - is intersects the left edge
*
* @param el Element
* @return {Object} ViewportInfo
*/
function getElementViewportInfo(el) {
let result = {};
let rect = el.getBoundingClientRect();
let windowHeight = window.innerHeight || document.documentElement.clientHeight;
let windowWidth = window.innerWidth || document.documentElement.clientWidth;
let insideX = rect.left >= 0 && rect.left + rect.width <= windowWidth;
let insideY = rect.top >= 0 && rect.top + rect.height <= windowHeight;
result.isInsideViewport = insideX && insideY;
let aroundX = rect.left < 0 && rect.left + rect.width > windowWidth;
let aroundY = rect.top < 0 && rect.top + rect.height > windowHeight;
result.isAroundViewport = aroundX && aroundY;
let onTop = rect.top < 0 && rect.top + rect.height > 0;
let onRight = rect.left < windowWidth && rect.left + rect.width > windowWidth;
let onLeft = rect.left < 0 && rect.left + rect.width > 0;
let onBottom = rect.top < windowHeight && rect.top + rect.height > windowHeight;
let onY = insideY || aroundY || onTop || onBottom;
let onX = insideX || aroundX || onLeft || onRight;
result.isOnTopEdge = onTop && onX;
result.isOnRightEdge = onRight && onY;
result.isOnBottomEdge = onBottom && onX;
result.isOnLeftEdge = onLeft && onY;
result.isOnEdge = result.isOnLeftEdge || result.isOnRightEdge ||
result.isOnTopEdge || result.isOnBottomEdge;
let isInX =
insideX || aroundX || result.isOnLeftEdge || result.isOnRightEdge;
let isInY =
insideY || aroundY || result.isOnTopEdge || result.isOnBottomEdge;
result.isInViewport = isInX && isInY;
result.isPartiallyInViewport =
result.isInViewport && result.isOnEdge;
return result;
}
我尝试了Dan的答案，然而，用于确定边界的代数意味着元素必须既≤视口大小，又完全在视口内才能为真，很容易导致假否定。如果你想确定一个元素是否在视口中，ryanve的答案是接近的，但被测试的元素应该与视口重叠，所以试试这个:
function isElementInViewport(el) {
var rect = el.getBoundingClientRect();
return rect.bottom > 0 &&
rect.right > 0 &&
rect.left < (window.innerWidth || document.documentElement.clientWidth) /* or $(window).width() */ &&
rect.top < (window.innerHeight || document.documentElement.clientHeight) /* or $(window).height() */;
}
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>
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…
我在这里遇到的所有答案都只是检查元素是否位于当前视口中。但这并不意味着它是可见的。 如果给定的元素在一个包含满溢内容的div中，并且它被滚动到视图之外，该怎么办?
要解决这个问题，您必须检查元素是否被所有父元素所包含。 我的解决方案就是这样:
它还允许您指定多少元素必须是可见的。
Element.prototype.isVisible = function(percentX, percentY){
var tolerance = 0.01; //needed because the rects returned by getBoundingClientRect provide the position up to 10 decimals
if(percentX == null){
percentX = 100;
}
if(percentY == null){
percentY = 100;
}
var elementRect = this.getBoundingClientRect();
var parentRects = [];
var element = this;
while(element.parentElement != null){
parentRects.push(element.parentElement.getBoundingClientRect());
element = element.parentElement;
}
var visibleInAllParents = parentRects.every(function(parentRect){
var visiblePixelX = Math.min(elementRect.right, parentRect.right) - Math.max(elementRect.left, parentRect.left);
var visiblePixelY = Math.min(elementRect.bottom, parentRect.bottom) - Math.max(elementRect.top, parentRect.top);
var visiblePercentageX = visiblePixelX / elementRect.width * 100;
var visiblePercentageY = visiblePixelY / elementRect.height * 100;
return visiblePercentageX + tolerance > percentX && visiblePercentageY + tolerance > percentY;
});
return visibleInAllParents;
};
这个解决方案忽略了元素可能由于其他因素而不可见的事实，比如不透明度:0。
我已经在Chrome和Internet Explorer 11中测试了这个解决方案。
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