所以我找到了最可行的方法:

function visible(elm) {
  if(!elm.offsetHeight && !elm.offsetWidth) { return false; }
  if(getComputedStyle(elm).visibility === 'hidden') { return false; }
  return true;
}

这是基于以下事实:

显示:所有元素(即使是嵌套的元素)都没有宽度和高度。 可见性即使对于嵌套的元素也是隐藏的。

因此不需要测试offsetParent或在DOM树中循环来测试哪个父对象具有可见性:hidden。这应该可以在ie9中工作。

你可能会说，如果透明度:0和折叠的元素(有宽度但没有高度-反之亦然)也不是真正可见的。但话说回来，它们并不是隐藏的。

如果你正在抓取网站，一个非常低效的方法对我来说是突出显示任何元素，然后截图，然后检查截图是否发生了变化。

//Screenshot

function makeSelected(element){
    let range = new Range()
    range.selectNode(element)
    let selection = window.getSelection()
    selection.removeAllRanges()
    selection.addRange(range)
}
// screenshot again and check for diff

根据MDN文档，元素的offsetParent属性将在它或它的任何父元素通过display style属性被隐藏时返回null。只要确保元素不是固定的。一个脚本来检查这个，如果你没有位置:fixed;页面上的元素可能是这样的:

// Where el is the DOM element you'd like to test for visibility
function isHidden(el) {
    return (el.offsetParent === null)
}

另一方面，如果您确实有位置固定的元素可能会在此搜索中被捕获，那么您将不得不遗憾地(并且缓慢地)使用window.getComputedStyle()。这种情况下的函数可能是:

// Where el is the DOM element you'd like to test for visibility
function isHidden(el) {
    var style = window.getComputedStyle(el);
    return (style.display === 'none')
}

选项2可能更简单一点，因为它考虑了更多的边缘情况，但我打赌它也会慢很多，所以如果你不得不多次重复这个操作，最好避免它。

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.

我有一个更有效的解决方案相比AlexZ的getComputedStyle()解决方案时，有位置“固定”元素，如果一个愿意忽略一些边缘情况(检查评论):

function isVisible(el) {
    /* offsetParent would be null if display 'none' is set.
       However Chrome, IE and MS Edge returns offsetParent as null for elements
       with CSS position 'fixed'. So check whether the dimensions are zero.

       This check would be inaccurate if position is 'fixed' AND dimensions were
       intentionally set to zero. But..it is good enough for most cases.*/
    return Boolean(el.offsetParent || el.offsetWidth || el.offsetHeight);
}

附注:严格来说，“可见性”首先需要定义。在我的情况下，我正在考虑一个元素可见，只要我可以运行所有DOM方法/属性上没有问题(即使不透明度为0或CSS可见性属性是“隐藏”等)。

下面是一个(纯纯的JS)函数，它执行大量的检查，确保给定的元素对用户可见:

function isVisible(element) {
    // Check if the element is null or undefined
    if (!element) return false;

    // Get the element's bounding client rect
    const boundingRect = element.getBoundingClientRect();

    // Check if the element has a positive width and height
    if (boundingRect.width <= 0 || boundingRect.height <= 0) return false;

    // Check if the element's top and left values are within the viewport
    const top = boundingRect.top;
    const left = boundingRect.left;
    const viewportWidth = window.innerWidth || document.documentElement.clientWidth;
    const viewportHeight = window.innerHeight || document.documentElement.clientHeight;
    if (top > viewportHeight || left > viewportWidth) return false;

    // Check if the element's right and bottom values are within the viewport
    const right = boundingRect.right;
    const bottom = boundingRect.bottom;
    if (right < 0 || bottom < 0) return false;

    // Check if the element is hidden by the overflow property
    const parentNode = element.parentNode;
    if (parentNode && getComputedStyle(parentNode).overflow === 'hidden') {
        const parentRect = parentNode.getBoundingClientRect();
        if (top < parentRect.top || bottom > parentRect.bottom || left < parentRect.left || right > parentRect.right) {
            return false;
        }
    }

    const elementComputedStyle = getComputedStyle(element);

    // Check if the element has a z-index of less than 0
    const zIndex = elementComputedStyle.zIndex;
    if (zIndex < 0) return false;

    // Check if the element has a display value of 'none' or an opacity of 0
    const display = elementComputedStyle.display;
    const opacity = elementComputedStyle.opacity;
    if (display === 'none' || opacity === '0') return false;

    // Check if the element is hidden by an ancestor element with a display value of 'none' or an opacity of 0
    let ancestorElement = element.parentElement;
    while (ancestorElement) {
        const ancestorComputedStyle = getComputedStyle(ancestorElement);
        const ancestorDisplay = ancestorComputedStyle.display;
        const ancestorOpacity = ancestorComputedStyle.opacity;
        if (ancestorDisplay === 'none' || ancestorOpacity === '0') return false;
        ancestorElement = ancestorElement.parentElement;
    }

    // Initialize a variable to keep track of whether the element is obscured by another element
    let obscured = false;

    // Check if the element is obscured by another element according to its position
    if (elementComputedStyle.position === 'absolute' || elementComputedStyle.position === 'fixed' ||
        elementComputedStyle.position === 'relative' || elementComputedStyle.position === 'sticky' ||
        elementComputedStyle.position === 'static') {
        let siblingElement = element.nextElementSibling;
        while (siblingElement) {
            if (siblingElement.getBoundingClientRect().top > boundingRect.bottom || siblingElement.getBoundingClientRect().left > boundingRect.right) {
                break;
            }
            if (siblingElement.getBoundingClientRect().bottom > boundingRect.top && siblingElement.getBoundingClientRect().right > boundingRect.left) {
                obscured = true;
                break;
            }
            siblingElement = siblingElement.nextElementSibling;
        }
        if (obscured) return false;
    }

    // If all checks have passed, the element is visible
    return true;
}