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

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)。

其他回答

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;
}

const isVisible = (selector) => { let selectedElement let topElement let selectedData selectedElement = document.querySelector(selector) if (!selectedElement) { return false } selectedData = selectedElement.getBoundingClientRect() if (!selectedData || !Object.keys(selectedData)) { return false } if (!(selectedData.width > 0) || !(selectedData.height > 0)) { return false } topElement = document.elementFromPoint(selectedData.top, selectedData.left) if (selectedElement !== topElement) { return false } return true } const output = document.querySelector('.text') output.innerHTML = '.x element is visible: ' + isVisible('.x') .block { width: 100px; height: 100px; background: black; } .y { background: red; margin-top: -100px; } <div class="text"></div> <div class="x block"></div> <div class="y block"></div>

Chrome 105(以及Edge和Opera)和Firefox 106引入了element . checkvisibility(),如果元素是可见的,则返回true,否则返回false。

该函数检查了使元素不可见的各种因素,包括display:none、可见性、内容可见性和不透明度:

let element = document.getElementById("myIcon");
let isVisible = element.checkVisibility({
    checkOpacity: true,      // Check CSS opacity property too
    checkVisibilityCSS: true // Check CSS visibility property too
});

旁注:checkVisibility()以前被称为isVisible()。看这个GitHub问题。 参见这里的checkVisibility()规范草案。

对我来说,所有其他的解决方案在某些情况下都失效了。

获胜的答案如下:

http://plnkr.co/edit/6CSCA2fe4Gqt4jCBP2wu?p=preview

最终,我认为最好的解决方案是$(elem).is(':visible')——然而,这不是纯javascript。它是jquery..

所以我偷看了他们的来源,找到了我想要的

jQuery.expr.filters.visible = function( elem ) {
    return !!( elem.offsetWidth || elem.offsetHeight || elem.getClientRects().length );
};

这是来源:https://github.com/jquery/jquery/blob/master/src/css/hiddenVisibleSelectors.js

仅供参考,应该注意getBoundingClientRect()在某些情况下可以工作。

例如,使用display: none简单检查元素是否被隐藏,可能看起来像这样:

var box = element.getBoundingClientRect();
var visible = box.width && box.height;

这也很方便,因为它还涵盖了零宽度、零高度和位置:固定的情况。但是,它不应该报告使用opacity: 0或visibility: hidden隐藏的元素(但是也不会报告offsetParent)。