unstale

npm / chai

chai

What changed in chai 6, from its official release notes, upgrade guides and advisories. Sources checked 2026-10-18.

1 breaking1 new APIs and options1 behavior and defaults1 tooling5 fixes and other

See which of these apply to your code, ranked, in your agent:

npx @unstale/cli init

@unstale/cli on npm

chai 69 changes

Breaking changes 1

  • Iterable assertions require iterators to be callable.

    6.3.0release notes

New APIs and options 1

  • More utility type definitions are available to developers using Chai's types.

    6.3.0release notes

Behavior and default changes 1

Tooling 1

  • Chai's build target is now es2021 to support Safari versions earlier than 16.4.

    6.2.1release notes

Fixes and other changes 5

  • The change assertion's JSDoc types are corrected, and it handles 0 and empty string.

    6.3.0release notes

  • The keys() assertion considers only unique expected keys.

    6.3.0release notes

  • Literal template tags are preserved in assertion values.

    6.3.0release notes

  • The failure message for not.deep.oneOf now includes the not modifier.

    6.3.0release notes

  • Avoids a BigInt literal in closeTo for runtime compatibility.

    6.2.2release notes