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Use checkVisibility when filtering for focusables #17

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Merged
knuton merged 1 commit into from
Nov 4, 2025
Merged

Use checkVisibility when filtering for focusables #17

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6 changes: 3 additions & 3 deletions cypress/e2e/spec.cy.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -440,9 +440,9 @@ describe("focus-shift spec", () => {

it(
"ignores non-rendered elements",
testFor("./cypress/fixtures/non-rendered-elements.html", { className: "columns" }, [
{ eventType: "keydown", selector: "#first-button", options: keyevent({ key: "ArrowRight" }) },
{ eventType: "keydown", selector: "#last-button", options: keyevent({ key: "ArrowRight" }) }
testFor("./cypress/fixtures/non-rendered-elements.html", { className: "rows" }, [
{ eventType: "keydown", selector: "#first-button", options: keyevent({ key: "ArrowDown" }) },
{ eventType: "keydown", selector: "#last-button", options: keyevent({ key: "ArrowDown" }) }
])
)
})
53 changes: 45 additions & 8 deletions cypress/fixtures/non-rendered-elements.html
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,10 @@
.displayNone {
display: none;
}
.contentVisibilityHidden {
display: inline-block;
content-visibility: hidden;
}
.visibilityHidden {
visibility: hidden;
}
Expand All @@ -29,14 +33,47 @@
</style>
</head>
<body>
<button id="first-button">First Button</button>
<button class="opacityZero">Transparent Button</button>
<button class="displayNone">Hidden Button</button>
<button class="visibilityHidden">Hidden Button</button>
<button class="visibilityCollapse">Hidden Button</button>
<span tabindex="1" class="zeroWidth">Hidden Element</span>
<span tabindex="1" class="zeroHeight">Hidden Element</span>
<button id="last-button">Last Button</button>
<div class="nav-group">
<button id="first-button">First Visible Button</button>

<button class="opacityZero">Transparent Button</button>
<div class="opacityZero">
<div>
<span><button>Nested Transparent Button</button></span>
</div>
</div>

<button class="displayNone">Hidden Button</button>
<div class="displayNone">
<div>
<span><button>Nested Hidden Button</button></span>
</div>
</div>

<!-- Not yet supported by WebKit (16) on macos-latest GitHub runner as of November 2025
<span class="contentVisibilityHidden"><button>Non-Rendered Button</button></span>
-->

<button class="visibilityHidden">Hidden Button</button>
<div class="visibilityHidden">
<div>
<span><button>Nested Hidden Button</button></span>
</div>
</div>

<button class="visibilityCollapse">Nested Collapsed Button</button>
<div class="visibilityCollapse">
<div>
<span><button>Nested Collapsed Button</button></span>
</div>
</div>

<span tabindex="1" class="zeroWidth">Hidden Element</span>
<span tabindex="1" class="zeroHeight">Hidden Element</span>

<button id="last-button">Second Visible Button</button>
</div>

<script src="../../index.js"></script>
</body>
</html>
85 changes: 55 additions & 30 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -99,7 +99,7 @@ function focusInitial(direction, container) {
.filter(hasTabIndex)
.filter((elem) => elem.tabIndex > 0)
const markedElement = getMinimumBy(tabindexed, (elem) => elem.tabIndex)
if (markedElement != null && isBeingRendered(markedElement)) {
if (markedElement != null && isVisible(markedElement)) {
return applyFocus(direction, makeVirtualOrigin(direction), markedElement)
}

Expand Down Expand Up @@ -171,51 +171,76 @@ function isFocusable(element) {
// Descends from closed details element
if (hasClosedDetailsAncestor(element)) return false

return isBeingRendered(element)
return isVisible(element)
}

/**
* Decide whether an element is being rendered or not.
* Decide whether an element should count as visible.
*
* An element is not being rendered if:
* 1. An element has the style "visibility: hidden | collapse" or "display: none". (Note: these are inherited.)
* 2. An element has the style "opacity: 0". (Somewhat of a white lie, as it will still affect layout.)
* 3. The width or height of an element is explicitly set to 0.
* 4. An element's parent is hidden.
* Our definition of visible is essentially that of the `checkVisibility` web API, but in addition
* we count elements with a zero-size dimension as invisible.
*
* @see {@link https://html.spec.whatwg.org/multipage/rendering.html#being-rendered}
* @function isBeingRendered
* @param element {Element}
* @returns {boolean}
*/
function isVisible(element) {
if (!checkVisibility(element)) {
return false
}

function isBeingRendered(element) {
if (element.parentElement) {
const parentStyle = window.getComputedStyle(element.parentElement, null)
if (hasHidingStyleProperty(parentStyle)) return false
if (element instanceof HTMLElement) {
if (element.offsetWidth === 0 || element.offsetHeight === 0) return false
}
const elementStyle = window.getComputedStyle(element, null)
if (
hasHidingStyleProperty(elementStyle) ||
elementStyle.getPropertyValue("width") === "0px" ||
elementStyle.getPropertyValue("height") === "0px"
)
return false

return true
}

/**
* Determine if a style declaration has any properties that make an element hidden.
* @function hasHidingStyleProperty
* @param style {CSSStyleDeclaration}
* Determines whether an element is visible.
*
* This either defers to `Element.checkVisibility()` if available, or does a simple approximation
* of its spec. Returns `true` if the element has a box and is not hidden, fully transparent, or
* skipped due to content-visibility.
*
* @see {@link https://drafts.csswg.org/cssom-view-1/#dom-element-checkvisibility}
* @param element {Element}
* @returns {boolean}
*/
function hasHidingStyleProperty(style) {
return (
style.getPropertyValue("display") === "none" ||
["hidden", "collapse"].includes(style.getPropertyValue("visibility")) ||
style.getPropertyValue("opacity") === "0"
)
function checkVisibility(element) {
if (typeof element.checkVisibility === "function") {
const checkAll = {
checkOpacity: true,
checkVisibilityCSS: true,
// With content-visibility auto, though hidden, "the skipped contents must still be available
// as normal to user-agent features such as find-in-page, tab order navigation, etc., and must
// be focusable and selectable as normal."
// https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties/content-visibility#auto
contentVisibilityAuto: false,
opacityProperty: true,
visibilityProperty: true
}
return element.checkVisibility(checkAll)
}

// Approximate checkVisibility
if (!element.isConnected) return false

/** @type {Element | null} */
let iter = element
while (iter != null && iter.nodeType === 1) {
const style = getComputedStyle(iter)

if (style.display === "none") return false
if ("contentVisibility" in style && style.contentVisibility === "hidden")
return false
if (style.opacity === "0") return false
if (style.visibility === "hidden" || style.visibility === "collapse")
return false

iter = iter.parentElement
}

return true
}

/**
Expand Down