tc39/proposal-type-annotations resource

Health v2 · maintenance only

Flags: no_releases no_license

Adoption not part of the score

4386 stars · 52 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

A Stage 1 TC39 proposal to add erasable type annotation syntax to ECMAScript, so JavaScript engines treat type syntax as comments. It aims to let developers run TypeScript- or Flow-style code without a transpilation build step.

Use cases

• run TypeScript code in the browser without transpiling
• remove a build step from JavaScript apps using type syntax
• standardize type annotation syntax across JS type checkers
• track the status of the types-as-comments ECMAScript proposal
• understand how engines would erase type syntax at runtime

When to choose

• you want to follow or contribute to the standardization of type syntax in JavaScript
• you are researching how JS engines could support erasable types natively
• you are evaluating the future of TypeScript/Flow interoperability with plain JS

When to avoid

• you need a working type checker today - use TypeScript or Flow instead
• you need a production-ready tool or library - this is only a specification proposal
• you need runtime type validation - the proposal explicitly erases types

Facets

learning-resource · maturity experimental

programming-language type-system compiler programming-languages web-development developer-tools cross-platform ecmascript-proposal tc39 typescript type-annotations stage-1 specification

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markdown · JSON · MCP: product_card(name="tc39/proposal-type-annotations")