Skip to content[5.4.0] - 2026-08-25
Added
- Added the
scalarStyleRules dumper option to customize string formatting.
See Scalar styling for details.
Changed
- [breaking] Flattened the low-level AST node style representation. Scalar
and collection nodes now use
SCALAR_STYLE and COLLECTION_STYLE values;
explicit tags use the separate tagged property. Alias nodes now contain
only kind and anchor. This only affects code that directly constructs or
edits AST nodes.
- [breaking] The
sortKeys option was rewritten using AST mutation to avoid
side effects.
- Reworked scalar style selection. This can change formatting without changing
loaded values; in particular, whitespace-only strings are now double-quoted.
Fixed
- Accept a byte order mark at the start of each document in a stream, #791.
- Produce valid flow mappings with
quoteFlowKeys and flowSkipColonSpace,
including alias and property-only keys, #786.
- Preserve empty scalar items when converting block sequences to flow style.
- Do not apply the 1024-character simple-key limit to flow mapping keys.
- Count Unicode code points, rather than UTF-16 code units, for the
1024-character simple-key limit.
- Add an explicit document-end marker after keep-chomped block scalars when
needed to preserve trailing newlines.