js-yaml

Added the scalarStyleRules dumper option to customize string formatting. See Scalar styling for details.

Add an explicit document-end marker after keep-chomped block scalars when needed to preserve trailing newlines.

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.

Added completely new documentation.

Exported DUMP_SCHEMA, the default schema used by the dumper.

Added YAMLException.throwAt() for throwing an error at a source position.

Validate << sequence items at merge time, so aliased merge sources are checked too.

Resolve << outside of a mapping key as the plain string '<<', matching v4, instead of leaking an internal symbol into the result.

Prevent prototype fallback when resolving tags and mapping entries, #782.

Resolve !!timestamp years 0000-0099 correctly, #775.

Preserve implicit null mapping values before document markers and reject unpaired mapping event streams, #784.

Preserve folded scalar values with tab-indented lines when round-tripping a parsed AST through present(); dump() and loading are unaffected, #780.

Quote flow scalars where a colon precedes a flow indicator, #773.

Add Map support to !!omap (should work when realMapTag used)

Added maxTotalMergeKeys (10000) loader option to limit the total number of keys processed by YAML merge (<<) across one load() / loadAll() call.

Added maxAliases (-1) loader option to limit the number of YAML aliases per document.

Round-trip of integers with exponential form (>= 1e21)

Collection tags can finalize an incrementally populated carrier into a different result value.