Isolate Distributed JavaScript (#1645)

Summary:
Pull Request resolved: #1645

Right now we publish Yoga by transforming in-place, and rewriting the entrypoint to point to the generated vanilla JavaScript.

It is nice to include the original source, e.g. so that users can use sourcemaps when debugging, but putting these files on top of each other has been causing problems, like #1637 (comment)

This changes the packaging step to instead put all the outputs into a "dist" folder, and point the package entrypoints there. We still include original source for sourcemap usage.

Reviewed By: yungsters

Differential Revision: D56093470

fbshipit-source-id: ecd52dddd9040294aae66747cf1fdf48c7f602e7

Author: NickGerleman

javascript/just.config.cjs

@@ -13,11 +13,11 @@ const {
   logger,
   jestTask,
   option,
-  parallel,
   series,
   spawn,
   task,
   tscTask,
+  copyTask,
 } = require('just-scripts');
 
 const {existsSync} = require('fs');
@@ -58,16 +58,32 @@ task('prepack-package-json', async () => {
   const packageJsonContents = await readFile(packageJsonPath);
   const packageJson = JSON.parse(packageJsonContents.toString('utf-8'));
 
-  recursiveReplace(packageJson, /(.\/src\/.*)\.ts/, '$1.js');
-  packageJson.types = packageJson.main.replace(/(.\/src\/.*)\.js/, '$1.d.ts');
+  packageJson.main = packageJson.main.replace(
+    /^.\/src\/(.*)\.ts/,
+    './dist/src/$1.js',
+  );
+  packageJson.types = packageJson.main.replace(/(.*)\.js/, '$1.d.ts');
+
+  recursiveReplace(
+    packageJson.exports,
+    /^.\/src\/(.*)\.ts/,
+    './dist/src/$1.js',
+  );
+
   await writeFile(packageJsonPath, JSON.stringify(packageJson, null, 2));
 });
 
 task(
   'prepack',
   series(
-    parallel('build', tscTask({emitDeclarationOnly: true})),
-    babelTransformTask({dir: 'src'}),
+    'build',
+    copyTask({paths: ['binaries'], dest: 'dist/binaries'}),
+    tscTask({
+      emitDeclarationOnly: true,
+      rootDir: '.',
+      declarationDir: 'dist',
+    }),
+    babelTransformTask({src: 'src', dst: 'dist/src'}),
     'prepack-package-json',
   ),
 );
@@ -85,14 +101,14 @@ function recursiveReplace(obj, pattern, replacement) {
 function babelTransformTask(opts) {
   return () => {
     const args = [
-      opts.dir,
+      opts.src,
       '--source-maps',
       '--out-dir',
-      opts.dir,
+      opts.dst,
       '--extensions',
       '.js,.cjs,.mjs,.ts,.cts,.mts',
     ];
-    logger.info(`Transforming "${path.resolve(opts.dir)}"`);
+    logger.info(`Transforming "${path.resolve(opts.src)}"`);
 
     return spawn(node, [require.resolve('@babel/cli/bin/babel'), ...args], {
       cwd: __dirname,

javascript/package.json

@@ -11,12 +11,14 @@
   },
   "type": "module",
   "main": "./src/index.ts",
+  "types": "./src/index.ts",
   "exports": {
     ".": "./src/index.ts",
     "./load": "./src/load.ts"
   },
   "files": [
-    "binaries/**",
+    "dist/binaries/**",
+    "dist/src/**",
     "src/**"
   ],
   "scripts": {