Sourced from js-yaml's changelog.

[5.2.0] - 2026-06-26

Added

• 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.

Removed

• maxMergeSeqLength replaced with maxTotalMergeKeys for limiting YAML merge processing.

Fixed

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

[5.1.0] - 2026-06-23

Added

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

Changed

• [breaking] quoteStyle now selects the preferred quote style; use the restored forceQuotes option to force quoting non-key strings.

[5.0.0] - 2026-06-20

Added

• Added named exports for schemas, tags, parser events and AST utilities.
• Reworked JSON_SCHEMA and CORE_SCHEMA with spec-compliant scalar resolution rules, and added YAML11_SCHEMA.
• Added realMapTag for lossless mappings with non-string and complex keys. Object-based mappings now reject complex keys instead of stringifying them.
• Added dump() transform option for changing the generated AST before rendering.
• Added dump() options seqInlineFirst, flowBracketPadding, flowSkipCommaSpace, flowSkipColonSpace, quoteFlowKeys, quoteStyle and tagBeforeAnchor.
• Added formal data layers (events and AST) for modular data pipelines.
  • Added low-level parser (to events), presenter and visitor APIs.
• Added the YAML Test Suite to the test set.

Changed

• See the migration guide for upgrade notes.
• Rewritten in TypeScript and reorganized the public API around flat named exports.
• Reduced the set of exported schemas:
  • YAML 1.2 schemas: CORE_SCHEMA (loader default), JSON_SCHEMA, FAILSAFE_SCHEMA.
  • YAML11_SCHEMA, a combination of all YAML 1.1 tags (YAML 1.1 does not specify a schema, only "types").

... (truncated)

• c28ed5e 5.2.0 released
• 125cd5a Add maxAliases option
• 3105455 Replace maxMergeSeqLengthoption with maxTotalMergeKeys (more robust)
• 39d00d6 numbers: Drop boxed numbers support, simplify .identify() checks, clarify rou...
• eb5cb5b fix: round-trip integers that stringify in exponential notation (#771)
• 89024c4 Update migration info, close #770
• f1e45cd 5.1.0 released
• 53b22be Fix constructor coverage
• a1eaa2b Fix quote style options and restore forceQuotes
• 0532e7d Add finalizers for immutable collection tags
• Additional commits viewable in compare view