Four public suites, both compatibility lanes, per platform. Every number below is generated from each suite's own output by the project's conformance tool — nothing here is hand-typed, and a build-time guard fails if the figures drift from the last run. They read low on purpose: this is a typed subset compiler, and most of these corpora are untyped eval-based JavaScript, browser DOM, or the whole Node platform — largely out of scope by design, not silent failures.
Figures for macOS (Apple Silicon), as of that platform's last committed conformance run.
The official ECMAScript conformance corpus, run unfiltered. Most of it is out of scope by design — eval-based assertions, Intl/Temporal, dynamic import — so the honest figure is the in-scope subset.
The browser platform’s own test suite, run headless through a testharness shim. It is dominated by DOM/rendering tests this compiler doesn’t target, so the runnable-document figure is low by design — shown for the JS/encoding/URL corners that do apply.
Agreement with tsc’s own accept/reject verdict over Microsoft’s compiler and conformance test cases — a measure of front-end fidelity, not runtime behavior.
How much of Node’s own behavioral test suite runs verbatim after a mechanical CommonJS→typed-ESM transform — a floor on Node fidelity, not a coverage claim.
Want the caveats behind the targeted-feature numbers, and the per-flag lane taglines? See the coverage matrix → The repository's generated conformance reports are the source of truth.