Do not emit multiple UTF-8 BOM markers - #2136
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8.5.24 restored a leading BOM on stringify. Concatenated CSS and documents with several BOM-tagged roots then contained U+FEFF in the middle of the output. Strip every leading BOM on parse, skip stray markers while tokenizing, and emit at most one BOM when stringifying. Fixes postcss#2133
ai
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Aug 14, 2026
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| function nextToken(opts) { | ||
| if (returned.length) return returned.pop() | ||
| skipBom() |
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Why do we need it if we already have this.css.replace(/^[\uFEFF\uFFFE]+/, '')?
De-ASI-INTERFACE
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Aug 14, 2026
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Why
v8.5.24 started restoring a leading BOM on stringify (#2119). That is correct for a single file, but
parse/stringifycould still produce more than one U+FEFF:a{}\uFEFFb{}) re-emitted the mid-file marker as part of the next selectorDocumentof several BOM-tagged roots wrote a BOM before every rootThose extra markers show up in the middle of generated CSS and break the first rule after each one.
Solution
Input, not only the firstStringifier#rootA single leading BOM is still preserved.
parse('\uFEFFa{}').toString()remains\uFEFFa{}.Fixes #2133