Refactor and convert JS codebase to ESM (#6899)

Co-authored-by: Christoph Knittel <christoph@knittel.cc>

Author: cometkim

.github/workflows/ci.yml

@@ -45,6 +45,11 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      - name: Use Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version-file: .nvmrc
+
       - name: Restore build cache
         id: build-cache
         uses: actions/cache@v4
@@ -401,11 +406,11 @@ jobs:
         run: |
           opam exec -- node packages/playground-bundling/scripts/generate_cmijs.js
           opam exec -- dune build --profile browser
-          cp ./_build/default/compiler/jsoo/jsoo_playground_main.bc.js playground/compiler.js
+          cp ./_build/default/compiler/jsoo/jsoo_playground_main.bc.js playground/compiler.cjs
 
       - name: Test playground compiler
         if: matrix.build_playground
-        run: node playground/playground_test.js
+        run: node playground/playground_test.cjs
 
       - name: Upload playground compiler to CDN
         if: ${{ matrix.build_playground && startsWith(github.ref, 'refs/tags/v') }}

.github/workflows/get_artifact_dir_name.js

@@ -1,10 +1,10 @@
-const fs = require("fs");
-const os = require("os");
+import * as fs from "node:fs";
+import * as os from "node:os";
 
-const { dirName: artifactDirName } = require("../../cli/bin_path.js");
+import { platformName } from "#cli/bins";
 
 // Pass artifactDirName to subsequent GitHub actions
 fs.appendFileSync(
   process.env.GITHUB_ENV,
-  `artifact_dir_name=${artifactDirName}${os.EOL}`,
+  `artifact_dir_name=${platformName}${os.EOL}`,
 );

.github/workflows/prepare_package_upload.js

@@ -1,7 +1,8 @@
-const fs = require("fs");
-const os = require("os");
+import * as fs from "node:fs";
+import * as os from "node:os";
+
+import packageSpec from "rescript/package.json" with { type: "json" };
 
-const packageSpec = require("rescript/package.json");
 const { version } = packageSpec;
 
 const commitHash = process.argv[2] || process.env.GITHUB_SHA;

.gitignore

@@ -72,7 +72,7 @@ playground/stdlib/
 playground/*.cmj
 playground/*.cmi
 playground/.netrc
-playground/compiler.js
+playground/compiler.*js
 
 rewatch/target/
 rewatch/rewatch
@@ -88,3 +88,5 @@ tests/analysis_tests/**/*.bs.js
 !.yarn/releases
 !.yarn/sdks
 !.yarn/versions
+
+*.tsbuildinfo

.yarnrc.yml

@@ -3,3 +3,5 @@ yarnPath: .yarn/releases/yarn-4.7.0.cjs
 nodeLinker: node-modules
 
 nmMode: hardlinks-global
+
+defaultSemverRangePrefix: ""

CHANGELOG.md

@@ -19,6 +19,7 @@
 #### :house: Internal
 
 - Remove `Stdlib_Char` module for now. https://github.com/rescript-lang/rescript/pull/7367
+- Convert internal JavaScript codebase into ESM, ReScript package itself is now ESM (`"type": "module"`). https://github.com/rescript-lang/rescript/pull/6899
 
 # 12.0.0-alpha.10
 

CONTRIBUTING.md

@@ -263,7 +263,7 @@ $ node
 
 ### Testing the Playground bundle
 
-Run `node playground/playground_test.js` for a quick sanity check to see if all the build artifacts are working together correctly. When releasing the playground bundle, the test will always be executed before publishing to catch regressions.
+Run `node playground/playground_test.cjs` for a quick sanity check to see if all the build artifacts are working together correctly. When releasing the playground bundle, the test will always be executed before publishing to catch regressions.
 
 ### Working on the Playground JS API
 
@@ -273,7 +273,7 @@ Whenever you are modifying any files in the ReScript compiler, or in the `jsoo_p
 make playground
 
 # optionally run your test / arbitrary node script to verify your changes
-node playground/playground_test.js
+node playground/playground_test.cjs
 ```
 
 ### Publishing the Playground Bundle on our KeyCDN

Makefile

@@ -61,7 +61,7 @@ artifacts: lib
 # Builds the core playground bundle (without the relevant cmijs files for the runtime)
 playground:
 	dune build --profile browser
-	cp ./_build/default/compiler/jsoo/jsoo_playground_main.bc.js playground/compiler.js
+	cp ./_build/default/compiler/jsoo/jsoo_playground_main.bc.js playground/compiler.cjs
 
 # Creates all the relevant core and third party cmij files to side-load together with the playground bundle
 playground-cmijs: artifacts
@@ -70,7 +70,7 @@ playground-cmijs: artifacts
 # Builds the playground, runs some e2e tests and releases the playground to the
 # CDN (requires KEYCDN_USER and KEYCDN_PASSWORD set in the env variables)
 playground-release: playground playground-cmijs
-	node playground/playground_test.js
+	node playground/playground_test.cjs
 	sh playground/upload_bundle.sh
 
 format:
@@ -86,7 +86,7 @@ clean-rewatch:
 	cargo clean --manifest-path rewatch/Cargo.toml && rm -f rewatch/rewatch
 
 clean:
-	(cd runtime && ../cli/rescript clean)
+	(cd runtime && ../cli/rescript.js clean)
 	dune clean
 
 clean-all: clean clean-gentype clean-rewatch 

analysis/examples/example-project/types.json

@@ -8,6 +8,6 @@
     }
   ],
   "custom": [
-    {"module": "Belt_HashMapInt", "path": [], "name": "t", "args": 1}
+    { "module": "Belt_HashMapInt", "path": [], "name": "t", "args": 1 }
   ]
-}
+}