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js-yaml

5.5.0 · 15 Oct 2026MIT322.7M / weekRepositoryHomepagenpmAtom feed

Your version

5.3.0

14 Aug 2026Where it was published

5.5.0 is the newest release of 5.x.

In short

1 breaking1 deprecated3 new2 fixed2 changed

  • breaking

    Removed the MERGE_KEY export (not used anymore after last fixes).

  • deprecated

    Deprecated flat constant exports. Use grouped ones instead.

Security

1 advisory affects 5.3.0; 5.4.1 fixes them

Release note

This release focuses on reworking the documentation and making small
architectural improvements before moving forward.

Added

  • 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.

Changed

  • Changed flat constant exports to grouped exports: EVENT_ID, SCALAR_STYLE,
    COLLECTION_STYLE, and CHOMPING_MODE, along with their value types. The old
    exports are still preserved, but deprecated.

  • Made identify mandatory for custom tag definitions. Use
    identify: () => false for load-only tags.

Deprecated

  • deprecated

    Deprecated flat constant exports. Use grouped ones instead.

Removed

  • breaking

    Removed the MERGE_KEY export (not used anymore after last fixes).

Fixed

  • 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.