# What changed in jsii > 29 changes in jsii 5 to 6 from its official release notes, upgrade guides and advisories: 2 breaking, 1 security, 7 new APIs and options. Each one cited. Sources checked 2026-10-29. HTML: https://unstale.sh/npm/jsii/ To see which of these apply to a repository, run `npx @unstale/cli init` in it. ## jsii 6 ### New APIs and options - The CLI reads validate-tsconfig defaults from package.json. (6.0.4) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v6.0.4) - Commands were added to validate a tsconfig and inspect tsconfig rule sets. (6.0.0) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v6.0.0) ### Tooling - TypeScript 6.0 support was added, allowing developers to use this TypeScript release with jsii. (6.0.0) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v6.0.0) ### Fixes and other changes - Fixes deprecation warnings that can get very repetitive. (5.9.54, 6.0.14) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v6.0.14), [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.54) - Fixed symbolId resolution for consumers when a library uses jsii.tsconfig. (5.9.51, 6.0.9) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v6.0.9), [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.51) - Emit metadata.tscRootDir relative to the package root. (5.9.49, 6.0.7) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v6.0.7), [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.49) - `@jsii ignore` now has an effect on types extending mapped types. (5.9.48, 6.0.5) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v6.0.5), [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.48) - Fixes parsing tsconfig.json files with leading comments. (6.0.3) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v6.0.3) ## jsii 5 ### Breaking changes - Index signatures, previously silently ignored and unavailable in non-JavaScript/TypeScript APIs, now cause an error unless explicitly opted out. (5.0.0) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.0.0) - Tuple types, previously interpreted as synonyms to object and resulting in unusable APIs for non-JavaScript/TypeScript languages, now cause an error. (5.0.0) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.0.0) ### Security - Fixes packages not being released with npm provenance attestations. (5.9.43) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.43) ### New APIs and options - Warnings can now be suppressed inline with the @jsii suppress directive. (5.9.29) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.29) - Warnings can now be silenced by JSII code, number, or diagnostic name. (5.9.29) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.29) - Namespaces can now be configured for files-as-submodules, in addition to directories. (5.8.23, 5.9.13) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.8.23), [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.13) - Intersection types are supported, allowing developers to express types that satisfy multiple type constraints. (5.8.22) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.8.22) - Use the @jsii ignore doc-tag to explicitly opt index signatures out of the multi-language API. (5.0.0) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.0.0) ### Behavior and default changes - Submodule target configurations are now validated. (5.8.23, 5.9.14) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.8.23), [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.14) - Classes can use covariant overrides. (5.8.22, 5.9.10) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.8.22), [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.10) ### Tooling - Compilation output now includes error and warning counts and timing. (5.9.29) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.29) ### Fixes and other changes - Fixed broken transitive deprecation warnings. (5.9.37) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.37) - Fixed the issue where the deprecation warnings source file was too large. (5.9.36) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.36) - Fixed cyclic dependencies generated in the warnings.js file. (5.9.36) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.36) - Submodule name collision detection no longer incorrectly triggers for names from a different submodule hierarchy level. (5.9.31) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.31) - Silenced warnings are excluded from the summary warning count. (5.9.29) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.29) - Detached diagnostics are now formatted with color. (5.9.29) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.29) - Detached diagnostics now include source locations. (5.9.29) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.29) - Diagnostic names now appear after the message text instead of after the source context. (5.9.29) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.29) - The types field is no longer required in package.json. (5.9.18) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.18) - Invalid jsii target parameters are now validated, helping developers catch invalid target configuration. (5.8.23, 5.9.12) — [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.8.23), [release notes](https://github.com/aws/jsii-compiler/releases/tag/v5.9.12)