有什么方法,我可以检查如果一个元素是可见的纯JS(没有jQuery) ?
因此,给定一个DOM元素,我如何检查它是否可见?我试着:
window.getComputedStyle(my_element)['display']);
但这似乎并不奏效。我想知道我应该检查哪些属性。我想到了:
display !== 'none'
visibility !== 'hidden'
还有我可能漏掉的吗?
有什么方法,我可以检查如果一个元素是可见的纯JS(没有jQuery) ?
因此,给定一个DOM元素,我如何检查它是否可见?我试着:
window.getComputedStyle(my_element)['display']);
但这似乎并不奏效。我想知道我应该检查哪些属性。我想到了:
display !== 'none'
visibility !== 'hidden'
还有我可能漏掉的吗?
当前回答
这是一种确定所有css属性(包括可见性)的方法:
html:
<div id="element">div content</div>
css:
#element
{
visibility:hidden;
}
javascript:
var element = document.getElementById('element');
if(element.style.visibility == 'hidden'){
alert('hidden');
}
else
{
alert('visible');
}
它适用于任何css属性,非常通用和可靠。
其他回答
来自http://code.jquery.com/jquery-1.11.1.js的jQuery代码有一个isHidden参数
var isHidden = function( elem, el ) {
// isHidden might be called from jQuery#filter function;
// in that case, element will be second argument
elem = el || elem;
return jQuery.css( elem, "display" ) === "none" || !jQuery.contains( elem.ownerDocument, elem );
};
因此,看起来有一个与所有者文档相关的额外检查
我想知道这是否真的适用于以下情况:
基于zIndex隐藏在其他元素后面的元素 完全透明的元素使它们不可见 位于屏幕外的元素(即左:-1000px) 具有可见性的元素:隐藏 有显示的元素:无 没有可见文本或子元素的元素 高度或宽度设置为0的元素
这可能会有帮助: 将元素隐藏在最左边的位置,然后检查offsetLeft属性。如果你想使用jQuery,你可以简单地检查:visible选择器并获得元素的可见状态。
HTML:
<div id="myDiv">Hello</div>
CSS:
<!-- for javaScript-->
#myDiv{
position:absolute;
left : -2000px;
}
<!-- for jQuery -->
#myDiv{
visibility:hidden;
}
javaScript:
var myStyle = document.getElementById("myDiv").offsetLeft;
if(myStyle < 0){
alert("Div is hidden!!");
}
jQuery:
if( $("#MyElement").is(":visible") == true )
{
alert("Div is visible!!");
}
js小提琴
var visible = document.getElementById("yourelementID's");
if (visible){
// make events
} else
{
//other events
}
2021的解决方案
根据MDN文档,交互观察器异步观察目标元素与祖先元素或顶级文档视口的交集中的变化。这意味着每当元素与视口相交时,交互观察器就会触发。
截至2021年,除IE外,目前所有浏览器都支持交集观测器。
实现
const el = document.getElementById("your-target-element");
const observer = new IntersectionObserver((entries) => {
if(entries[0].isIntersecting){
// el is visible
} else {
// el is not visible
}
});
observer.observe(el); // Asynchronous call
The handler will fire when initially created. And then it will fire every time that it becomes slightly visible or becomes completely not visible. An element is deemed to be not-visible when it's not actually visible within the viewport. So if you scroll down and element goes off the screen, then the observer will trigger and the // el is not visible code will be triggered - even though the element is still "displayed" (i.e. doesn't have display:none or visibility:hidden). What matters is whether there are any pixels of the element that are actually visible within the viewport.
改进了上面@Guy Messika的回答,如果中心点' X < 0是错误的,则中断并返回false,因为元素右侧可能会进入视图。这里有一个解决方案:
private isVisible(elem) {
const style = getComputedStyle(elem);
if (style.display === 'none') return false;
if (style.visibility !== 'visible') return false;
if ((style.opacity as any) === 0) return false;
if (
elem.offsetWidth +
elem.offsetHeight +
elem.getBoundingClientRect().height +
elem.getBoundingClientRect().width === 0
) return false;
const elementPoints = {
center: {
x: elem.getBoundingClientRect().left + elem.offsetWidth / 2,
y: elem.getBoundingClientRect().top + elem.offsetHeight / 2,
},
topLeft: {
x: elem.getBoundingClientRect().left,
y: elem.getBoundingClientRect().top,
},
topRight: {
x: elem.getBoundingClientRect().right,
y: elem.getBoundingClientRect().top,
},
bottomLeft: {
x: elem.getBoundingClientRect().left,
y: elem.getBoundingClientRect().bottom,
},
bottomRight: {
x: elem.getBoundingClientRect().right,
y: elem.getBoundingClientRect().bottom,
},
};
const docWidth = document.documentElement.clientWidth || window.innerWidth;
const docHeight = document.documentElement.clientHeight || window.innerHeight;
if (elementPoints.topLeft.x > docWidth) return false;
if (elementPoints.topLeft.y > docHeight) return false;
if (elementPoints.bottomRight.x < 0) return false;
if (elementPoints.bottomRight.y < 0) return false;
for (let index in elementPoints) {
const point = elementPoints[index];
let pointContainer = document.elementFromPoint(point.x, point.y);
if (pointContainer !== null) {
do {
if (pointContainer === elem) return true;
} while (pointContainer = pointContainer.parentNode);
}
}
return false;
}