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CSS: Return undefined for whitespace-only CSS variable values #5120

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Merged
mgol merged 1 commit into from
Oct 3, 2022
Merged

CSS: Return undefined for whitespace-only CSS variable values #5120

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28 changes: 24 additions & 4 deletions src/css/curCSS.js
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Original file line number Diff line number Diff line change
Expand Up @@ -12,17 +12,37 @@ function curCSS( elem, name, computed ) {

// getPropertyValue is needed for `.css('--customProperty')` (gh-3144)
if ( computed ) {
ret = computed.getPropertyValue( name ) || computed[ name ];

// trim whitespace for custom property (issue gh-4926)
if ( isCustomProp && ret !== undefined ) {
// Support: IE <=9 - 11+
// IE only supports `"float"` in `getPropertyValue`; in computed styles
// it's only available as `"cssFloat"`. We no longer modify properties
// sent to `.css()` apart from camelCasing, so we need to check both.
// Normally, this would create difference in behavior: if
// `getPropertyValue` returns an empty string, the value returned
// by `.css()` would be `undefined`. This is usually the case for
// disconnected elements. However, in IE even disconnected elements
// with no styles return `"none"` for `getPropertyValue( "float" )`
ret = computed.getPropertyValue( name ) || computed[ name ];

if ( isCustomProp && ret ) {

// Support: Firefox 105+, Chrome <=105+
// Spec requires trimming whitespace for custom properties (gh-4926).
// Firefox only trims leading whitespace. Chrome just collapses
// both leading & trailing whitespace to a single space.
//
// Fall back to `undefined` if empty string returned.
// This collapses a missing definition with property defined
// and set to an empty string but there's no standard API
// allowing us to differentiate them without a performance penalty
// and returning `undefined` aligns with older jQuery.
//
// rtrim treats U+000D CARRIAGE RETURN and U+000C FORM FEED
// as whitespace while CSS does not, but this is not a problem
// because CSS preprocessing replaces them with U+000A LINE FEED
// (which *is* CSS whitespace)
// https://www.w3.org/TR/css-syntax-3/#input-preprocessing
ret = ret.replace( rtrim, "$1" );
ret = ret.replace( rtrim, "$1" ) || undefined;
}

if ( ret === "" && !isAttached( elem ) ) {
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4 changes: 3 additions & 1 deletion test/unit/css.js
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Expand Up @@ -1748,6 +1748,7 @@ QUnit.testUnlessIE( "css(--customProperty)", function( assert ) {
" --prop10:\f\r\n\t val10 \f\r\n\t;\n" +
" --prop11:\u000C\u000D\u000A\u0009\u0020val11\u0020\u0009\u000A\u000D\u000C;\n" +
" --prop12:\u000Bval12\u000B;\n" +
" --space: ;\n" +
" --empty:;\n" +
" }\n" +
"</style>"
Expand All @@ -1757,7 +1758,7 @@ QUnit.testUnlessIE( "css(--customProperty)", function( assert ) {
$elem = jQuery( "<div>" ).addClass( "test__customProperties" )
.appendTo( "#qunit-fixture" ),
webkitOrBlink = /\bsafari\b/i.test( navigator.userAgent ),
expected = 19;
expected = 20;

if ( webkitOrBlink ) {
expected -= 2;
Expand Down Expand Up @@ -1803,6 +1804,7 @@ QUnit.testUnlessIE( "css(--customProperty)", function( assert ) {
assert.equal( $elem.css( "--prop10" ), "val10", "Multiple preceding and following escaped unicode whitespace trimmed" );
assert.equal( $elem.css( "--prop11" ), "val11", "Multiple preceding and following unicode whitespace trimmed" );
assert.equal( $elem.css( "--prop12" ), "\u000Bval12\u000B", "Multiple preceding and following non-CSS whitespace reserved" );
assert.equal( $elem.css( "--space" ), undefined );
assert.equal( $elem.css( "--empty" ), undefined );
assert.equal( $elem.css( "--nonexistent" ), undefined );
} );
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