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Add a fast path for comparing fields in “transition: all”. #57560

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chromium-wpt-export-bot merged 1 commit into from
Feb 4, 2026
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Add a fast path for comparing fields in “transition: all”. #57560

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82 changes: 82 additions & 0 deletions css/css-transitions/all-interpolates-same-as-explicit-property.html
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<!DOCTYPE html>
<html>
<head>
<title>transition:all interpolates the same as transition:the-actual-property</title>
<link rel="help" href="https://drafts.csswg.org/css-transitions/#transition-property-property">

<script src="/resources/testharness.js" type="text/javascript"></script>
<script src="/resources/testharnessreport.js" type="text/javascript"></script>
<script src="./support/helper.js" type="text/javascript"></script>

</head>
<body>
<div id="log"></div>

<script>
const cases = [
// Property name, from-value, to-value, transition at 50%
["width", "100px", "200px", "150px"],
["height", "100px", "200px", "150px"],
["z-index", "100", "200", "150"],
["display", "none", "block", "block"],
["margin-left", "100px", "200px", "150px"],
["font-kerning", "normal", "none", "none"],
["font-optical-sizing", "none", "auto", "auto"],
["font-size", "10px", "12px", "11px"],
["font-stretch", "100%", "150%", "125%"],
["font-style", "normal", "oblique 10deg", "oblique 5deg"],
["font-variant-ligatures", "common-ligatures", "none", "none"],
["font-variant-caps", "normal", "small-caps", "small-caps"],
["font-variant-east-asian", "normal", "ruby", "ruby"],
["font-variant-numeric", "normal", "slashed-zero", "slashed-zero"],
["font-weight", "400", "600", "500"],
["text-rendering", "none", "optimizespeed", "optimizespeed"],
["background-attachment", "scroll", "local", "local"],
["background-clip", "border-box", "text", "text"],
["background-image", "auto", "none", "none"],
["background-origin", "border-box", "padding-box", "padding-box"],
["background-position-x", "100px", "200px", "150px"],
["background-position-y", "100px", "200px", "150px"],
["background-repeat", "repeat-x", "repeat-y", "repeat-y"],
["background-size", "auto", "cover", "cover"],
["border-image-outset", "10px", "20px", "15px"],
["border-image-repeat", "stretch", "repeat", "repeat"],
["border-image-slice", "100", "200", "150"],
["border-image-width", "100px", "200px", "150px"],
["border-left-color", "black", "white", "rgb(128, 128, 128)"],
["counter-increment", "example-counter 10", "example-counter 20", "example-counter 20"],
["vertical-align", "10px", "20px", "15px"],
["vertical-align", "baseline", "super", "super"],
];

for (const c of cases) {
let propertyName = c[0];
let fromValue = c[1];
let toValue = c[2];
let midValue = c[3];
promise_test(async t => {
// Start a 100s transition 50% of the way through.
const div = addDiv(t, {
style: `transition: ${propertyName} 100s -50s linear allow-discrete; ${propertyName}: ${fromValue}`,
});
getComputedStyle(div)[propertyName];
div.style[propertyName] = toValue;
assert_equals(getComputedStyle(div)[propertyName],
midValue,
'Transition should be initially 50% complete');

// Now do the same with transition:all.
const div2 = addDiv(t, {
style: `transition: all 100s -50s linear allow-discrete; ${propertyName}: ${fromValue}`,
});
getComputedStyle(div2)[propertyName];
div2.style[propertyName] = toValue;
assert_equals(getComputedStyle(div2)[propertyName],
midValue,
'Transition should be initially 50% complete, with transition:all');
});
}
</script>

</body>
</html>