Blitz - WPT: nth-child-large-anplusb-clamp.html

wpt / css / selectors / nth-child-large-anplusb-clamp.html

Data from commit:
1884860 Copy-on-write style attribute blocks that are in the rule tree (#831) (2026-09-02)

Subtest	Status	Message
b term (NumberToken path) is clamped to INT_MAX	FAIL	cannot convert 'null' or 'undefined' to object
a term (DimensionToken path) is clamped to INT_MAX	FAIL	cannot convert 'null' or 'undefined' to object
b term following an a coefficient is clamped to INT_MAX	FAIL	cannot convert 'null' or 'undefined' to object

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/css/selectors/nth-child-large-anplusb-clamp.html

<!DOCTYPE html>
<html>
<head>
<title>CSS Selectors: large An+B coefficients in :nth-child() are clamped to the int range</title>
<link rel="help" href="https://drafts.csswg.org/selectors-4/#the-nth-child-pseudo">
<link rel="help" href="https://drafts.csswg.org/css-syntax-3/#anb-microsyntax">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<body>
<script>
// An+B coefficients in :nth-child() that overflow a 32-bit int must be clamped to
// the int range, not converted via an undefined double-to-int conversion. With
// clamping, huge positive values serialize to INT_MAX (2147483647). Without it the
// behavior is implementation-defined: on some architectures the value wraps to
// INT_MIN (-2147483648).

const INT_MAX = "2147483647";

function selectorTextFor(selector)
{
    const sheet = document.head.appendChild(document.createElement("style")).sheet;
    sheet.insertRule(selector + " { color: green; }", 0);
    return sheet.cssRules[0].selectorText;
}

test(() => {
    assert_equals(selectorTextFor(":nth-child(99999999999999999999)"), ":nth-child(" + INT_MAX + ")");
}, "b term (NumberToken path) is clamped to INT_MAX");

test(() => {
    assert_equals(selectorTextFor(":nth-child(99999999999999999999n)"), ":nth-child(" + INT_MAX + "n)");
}, "a term (DimensionToken path) is clamped to INT_MAX");

test(() => {
    assert_equals(selectorTextFor(":nth-child(2n+99999999999999999999)"), ":nth-child(2n+" + INT_MAX + ")");
}, "b term following an a coefficient is clamped to INT_MAX");
</script>
</body>
</html>