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typescript-to-js

A TypeScript-to-JavaScript converter removes type annotations and emits plain JS — useful for: showing TS code to a JS-only audience, embedding snippets where TS isn't supported, debugging compiled output, learning what TS adds vs JS, and quick removal of TS for prototyping in JS-only contexts. The ZTools TypeScript to JS Converter uses the official TypeScript compiler with configurable target (ES5 / ES2017 / ES2020 / ESNext), preserves comments, supports React TSX → JSX, and handles modern features (decorators, async/await, optional chaining).

Use cases​

StackOverflow / blog where TS isn't welcome​

Question/answer audience expects JS. Quick conversion strips types without manual work.

Quick prototyping in JS sandbox​

CodePen, JSFiddle don't support TS without setup. Strip types, paste, run.

Learning TypeScript​

See how TS code compiles to JS — understand what types add (none at runtime) and what TS does at compile time.

Debugging compile output​

Suspect a TS bug? See exactly what JS is being emitted; check for unexpected transformations.

How it works​

  1. Paste TypeScript — Standalone code, modules, classes, JSX/TSX all supported.
  2. Pick target ES version — ES5 (legacy compat), ES2017 (async/await native), ES2020 (optional chaining native), ESNext (latest).
  3. Pick module system — ES modules / CommonJS / UMD / None.
  4. Convert — TypeScript compiler removes types, optionally lowers syntax to target ES version.
  5. Copy / download — .js file ready to use.

Examples​

Input: function add(a: number, b: number): number \{ return a + b; \}

Output: function add(a, b) \{ return a + b; \} — types removed.

Input: TSX: const Btn = (props: \{ label: string \}) => <button>\{props.label\}</button>

Output: JSX: const Btn = (props) => <button>\{props.label\}</button> — types stripped, JSX preserved.

Input: Class with private fields, ES5 target

Output: IIFE-wrapped function with prototype methods — full lowering for old browsers.

Frequently asked questions​

Why does the output differ between targets?

TS lowers modern syntax to older equivalents. Target ES5: async/await becomes generator + Promise polyfill. Target ESNext: keep async/await as-is.

Are decorators preserved?

Yes — TS Stage 3 decorators emit cleanly to ES2022+. For earlier targets, lowered to function calls.

Will my JSX still work?

TSX → JSX strips types; JSX itself is preserved. Use a JSX-aware bundler (Vite, Webpack) to compile JSX → React.createElement calls.

What about type-only imports?

Removed entirely — they have no runtime effect. import type \{ User \} becomes nothing.

Will the JS run identically?

Yes — TS types are erased at compile, so the JS behaves the same. Only edge case: enum / namespace / decorator emit JS code that didn't exist in TS source.

How is this different from tsc?

Same compiler, browser-friendly UI. For a project, run tsc from CLI; for one-off conversion, this tool.

Tips​

  • Pick target ESNext for modern dev; ES5 only for legacy browser support.
  • Type-only imports (import type) are tree-shaken automatically.
  • JSX preserved — use a JSX bundler downstream.
  • For libraries, ship both: .ts source + compiled .js + .d.ts declarations.
  • For runtime-checked types, TS doesn't help — use Zod / io-ts / etc. for runtime validation.

Try it now​

The full typescript-to-js runs in your browser at https://ztools.zaions.com/typescript-to-js — no signup, no upload, no data leaves your device.

Open the tool ↗

Last updated: 2026-05-06 · Author: Ahsan Mahmood · Edit this page on GitHub