hatemhosny · Oct 12, 2026 · Oct 12, 2026 · Oct 12, 2026 · Oct 12, 2026 · Oct 12, 2026
diff --git a/README.md b/README.md
@@ -13,7 +13,7 @@ A [feature-rich](https://livecodes.io/docs/features/), open-source, **client-sid
 [![LiveCodes: npm version](https://img.shields.io/npm/v/livecodes)](https://www.npmjs.com/package/livecodes)
 [![LiveCodes: npm downloads](https://img.shields.io/npm/dm/livecodes)](https://www.npmjs.com/package/livecodes)
 [![LiveCodes: jsdelivr downloads](https://data.jsdelivr.com/v1/package/npm/livecodes/badge?style=rounded)](https://www.jsdelivr.com/package/npm/livecodes)
-[![LiveCodes: languages](https://img.shields.io/badge/languages-123-blue)](https://livecodes.io/docs/languages/)
+[![LiveCodes: languages](https://img.shields.io/badge/languages-124-blue)](https://livecodes.io/docs/languages/)
 [![LiveCodes: docs](https://img.shields.io/badge/Documentation-575757?logo=gitbook&logoColor=white)](https://livecodes.io/docs/)
 [![LiveCodes: llms.txt](https://img.shields.io/badge/llms.txt-575757?logo=googledocs&logoColor=white)](https://livecodes.io/docs/llms.txt)
 [![LiveCodes: llms-full.txt](https://img.shields.io/badge/llms--full.txt-575757?logo=googledocs&logoColor=white)](https://livecodes.io/docs/llms-full.txt)

diff --git a/docs/docs/languages/ocaml-js.mdx b/docs/docs/languages/ocaml-js.mdx
@@ -0,0 +1,93 @@
+# OCaml (JS)
+
+[OCaml](https://ocaml.org/) is an industrial-strength programming language supporting functional, imperative and object-oriented styles.
+
+LiveCodes runs the OCaml compiler itself, built with [js_of_ocaml](https://github.com/ocsigen/js_of_ocaml), so compilation happens in the browser and nothing is sent to a server. The compiler emits a JavaScript program, which the result page then runs.
+
+:::info Note
+
+LiveCodes also has an `ocaml` language, which runs the [ReScript](https://rescript-lang.org/) compiler. It is deprecated in favour of this one. Read documentation [here](./ocaml.mdx).
+
+:::
+
+## Demo
+
+import LiveCodes from '../../src/components/LiveCodes.tsx';
+
+export const params = {
+  'ocaml-js': 'let () =\n  print_endline "Hello, World!"\n',
+  console: 'full',
+};
+
+<LiveCodes params={params}></LiveCodes>
+
+## Usage
+
+LiveCodes runs OCaml in the browser, including the standard library.
+
+Because the compiled program *is* JavaScript by the time it runs, it can interact with the page. JavaScript interoperability and DOM access come from [js_of_ocaml](https://github.com/ocsigen/js_of_ocaml)'s `Js` and `Dom_html` with `open Js_of_ocaml` (see the [example below](#example-usage)).
+
+## Modules and Libraries
+
+The standard library is always available. Beyond it, these are linked on demand — the archive is fetched the first time a program names one of its modules, so a program that uses none of them downloads none of them.
+
+- **js_of_ocaml** — `Js`, `Dom_html`, and the rest of the browser APIs
+- **Str**, **Unix**, **Graphics** — from the OCaml distribution
+- **Lwt**, **js_of_ocaml-lwt** — promises and concurrency
+- **Re** — regular expressions
+- **jsonm**, **xmlm**, **uutf** — JSON, XML and Unicode text
+- **fmt**, **logs** — formatting and logging
+- **base64** — base64 encoding
+- **Zarith** — `Z` and `Q`, arbitrary-precision integers and rationals
+
+Everything here runs in the browser, so a library has to be pure OCaml, or have a JavaScript replacement for its C stubs — Zarith's are provided by `zarith_stubs_js`. Anything needing real threads, processes or a filesystem will not work, whatever is linked.
+
+This is the set built with the compiler. Other opam packages are not available.
+
+## Language Info
+
+### Name
+
+`ocaml-js`
+
+### Extensions
+
+`js.ocaml`, `js.ml`
+
+### Editor
+
+`script`
+
+## Compiler
+
+The OCaml compiler — the same `compiler-libs` frontend that compiles ordinary OCaml — compiled to JavaScript with [js_of_ocaml](https://github.com/ocsigen/js_of_ocaml). It is published as [@live-codes/ocaml](https://www.npmjs.com/package/@live-codes/ocaml).
+
+### Version
+
+`@live-codes/ocaml`: v0.2.0
+
+## Code Formatting
+
+Not supported.
+
+## Limitations
+
+There is no ppx support, since a ppx would have to run at compile time and compilation happens at run time here. So `##`, `##.` and `[%js]` are not available; use `Js.Unsafe` and the rest of the bindings instead.
+
+## Example Usage
+
+This example counts button clicks in the DOM, using `Dom_html`:
+
+<LiveCodes template="ocaml-js" height="80vh"></LiveCodes>
+
+## Starter Template
+
+https://livecodes.io/?template=ocaml-js
+
+## Links
+
+- [OCaml website](https://ocaml.org/)
+- [OCaml documentation](https://ocaml.org/docs/)
+- [@live-codes/ocaml on npm](https://www.npmjs.com/package/@live-codes/ocaml)
+- [js_of_ocaml](https://github.com/ocsigen/js_of_ocaml)
+- [OCaml with the ReScript compiler](./ocaml.mdx) in LiveCodes
diff --git a/docs/docs/languages/ocaml.mdx b/docs/docs/languages/ocaml.mdx
@@ -4,6 +4,14 @@
 
 LiveCodes compiles OCaml code to JavaScript using the [ReScript compiler](https://rescript-lang.org/). OCaml in LiveCodes supports JSX via a ReasonReact-compatible syntax.
 
+:::info Deprecation Note
+
+This language is deprecated in favour of [OCaml (JS)](./ocaml-js.mdx).
+
+To continue using this language use the language name `rescript-ocaml`.
+
+:::
+
 ## Usage
 
 ### Demo
@@ -66,6 +74,10 @@ OCaml React does not support React 19. Use an import map (in [custom settings](.
 
 `ocaml`
 
+### Aliases
+
+`rescript-ocaml`
+
 ### Extensions
 
 `.ml`, `.mli`

diff --git a/docs/src/components/LanguageSliders.tsx b/docs/src/components/LanguageSliders.tsx
@@ -77,6 +77,7 @@ export default function Sliders() {
       { name: 'elm', title: 'Elm' },
       { name: 'rescript', title: 'ReScript' },
       { name: 'reason', title: 'Reason' },
+      { name: 'ocaml-js', title: 'OCaml (JS)' },
       { name: 'ocaml', title: 'OCaml' },
       { name: 'nim', title: 'Nim' },
       { name: 'nim-wasm', title: 'Nim (Wasm)' },

diff --git a/docs/src/components/TemplateList.tsx b/docs/src/components/TemplateList.tsx
@@ -37,6 +37,7 @@ const templates = [
   { name: 'rescript', title: 'ReScript Starter', thumbnail: 'rescript.png' },
   { name: 'reason', title: 'Reason Starter', thumbnail: 'reason.svg' },
   { name: 'ocaml', title: 'Ocaml Starter', thumbnail: 'ocaml.svg' },
+  { name: 'ocaml-js', title: 'OCaml (JS) Starter', thumbnail: 'ocaml.svg' },
   { name: 'nim', title: 'Nim Starter', thumbnail: 'nim.svg' },
   { name: 'nim-wasm', title: 'Nim (Wasm) Starter', thumbnail: 'nim.svg' },
   { name: 'janet-wasm', title: 'Janet (Wasm) Starter', thumbnail: 'janet.png' },

diff --git a/e2e/specs/compilers.spec.ts b/e2e/specs/compilers.spec.ts
@@ -1494,6 +1494,30 @@ export class App {
 };`);
   });
 
+  test('OCaml (JS)', async ({ page, getTestUrl }) => {
+    await page.goto(getTestUrl());
+
+    const { app, getResult, waitForResultUpdate } = await getLoadedApp(page);
+
+    await app.click(':nth-match([title="Change Language"], 3)');
+    await (await app.$('[data-lang="ocaml-js"]'))?.click();
+    await waitForEditorFocus(app);
+    await page.keyboard.insertText(
+      [
+        'let () =',
+        '  let squares = List.init 5 (fun i -> i * i) in',
+        '  Printf.printf "sum=%d\\n" (List.fold_left (+) 0 squares)',
+      ].join('\n'),
+    );
+
+    await waitForResultUpdate();
+    const resultText = await getResult().innerHTML('body > script');
+
+    // The real OCaml compiler, compiled to JavaScript, emitted a bundle the page runs.
+    expect(resultText).toContain('// Generated by js_of_ocaml');
+    expect(resultText).toContain('sum=');
+  });
+
   test('LiveScript', async ({ page, getTestUrl, editor }) => {
     test.skip(editor === 'codejar', 'please fix');
 

diff --git a/functions/vendors/templates.js b/functions/vendors/templates.js
@@ -37,6 +37,7 @@ export const starterTemplates = {
   "rescript": "ReScript Starter",
   "reason": "Reason Starter",
   "ocaml": "Ocaml Starter",
+  "ocaml-js": "OCaml (JS) Starter",
   "nim": "Nim Starter",
   "nim-wasm": "Nim (Wasm) Starter",
   "crystal-wasm": "Crystal Starter",

diff --git a/scripts/build.js b/scripts/build.js
@@ -203,6 +203,7 @@ const esmBuild = () =>
       'languages/postgresql/lang-postgresql-compiler-esm.ts',
       'languages/duckdb/lang-duckdb-compiler-esm.ts',
       'languages/r/lang-r-script-esm.ts',
+      'languages/ocaml-js/lang-ocaml-js-compiler-esm.ts',
       'languages/rescript/lang-rescript-compiler-esm.ts',
       'i18n/i18n.ts',
     ]

diff --git a/server/php/inc/starter-templates.json b/server/php/inc/starter-templates.json
@@ -37,6 +37,7 @@
   "rescript": "ReScript Starter",
   "reason": "Reason Starter",
   "ocaml": "Ocaml Starter",
+  "ocaml-js": "OCaml (JS) Starter",
   "nim": "Nim Starter",
   "nim-wasm": "Nim (Wasm) Starter",
   "crystal-wasm": "Crystal Starter",

diff --git a/src/livecodes/UI/command-menu-actions.ts b/src/livecodes/UI/command-menu-actions.ts
@@ -293,6 +293,7 @@ export const getCommandMenuActions = ({
         'rescript',
         'reason',
         'ocaml',
+        'ocaml-js',
         'nim',
         'nim-wasm',
         'janet-wasm',