Make single 'build.js' to handle NPM package build

.babelrc.js

@@ -1,6 +1,3 @@
-//ignore all "__*__" directories, e.g. __tests__, __fixtures__
-const ignore = [/\/__[^/]*__\//]; // **/__*__
-
 module.exports = {
   presets: ['@babel/preset-env'],
   plugins: [
@@ -15,13 +12,11 @@ module.exports = {
       presets: [
         ['@babel/preset-env', { modules: 'commonjs' }],
       ],
-      ignore,
     },
     mjs: {
       presets: [
         ['@babel/preset-env', { modules: false }],
       ],
-      ignore,
     },
   },
 };

package.json

@@ -32,13 +32,7 @@
     "prettier": "prettier --write --list-different 'src/**/*.js'",
     "check": "flow check",
     "check-cover": "flow batch-coverage --quiet --strip-root --show-all src/ && flow stop --quiet",
-    "build": "npm run build:clean && npm run build:cp && npm run build:package-json && npm run build:cjs && npm run build:mjs && npm run build:flow",
-    "build:clean": "rm -rf ./dist && mkdir ./dist",
-    "build:cp": "cp README.md LICENSE ./dist",
-    "build:package-json": "node ./resources/copy-package-json.js",
-    "build:cjs": "babel src --env-name cjs --out-dir dist/",
-    "build:mjs": "babel src --env-name mjs --out-dir dist/module && for file in $(find dist/module -name '*.js'); do mv \"$file\" `echo \"$file\" | sed 's/dist\\/module/dist/g; s/.js$/.mjs/g'`; done && rm -rf dist/module",
-    "build:flow": "for file in $(find ./src -name '*.js' -not -path '*/__*__*'); do cp \"$file\" `echo \"$file\" | sed 's/\\/src\\//\\/dist\\//g'`.flow; done",
+    "build": "node resources/build.js",
     "preversion": ". ./resources/checkgit.sh && npm test",
     "prepublishOnly": ". ./resources/prepublish.sh",
     "gitpublish": ". ./resources/gitpublish.sh"
@@ -47,7 +41,6 @@
     "iterall": "^1.2.2"
   },
   "devDependencies": {
-    "@babel/cli": "7.4.4",
     "@babel/core": "7.4.4",
     "@babel/plugin-transform-flow-strip-types": "7.4.4",
     "@babel/polyfill": "7.4.4",

resources/build.js

@@ -0,0 +1,65 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @noflow
+ */
+
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const assert = require('assert');
+const babel = require('@babel/core');
+const {
+  copyFile,
+  writeFile,
+  rmdirRecursive,
+  mkdirRecursive,
+  readdirRecursive,
+} = require('./fs-utils');
+
+if (require.main === module) {
+  rmdirRecursive('./dist');
+  mkdirRecursive('./dist');
+
+  copyFile('./LICENSE', './dist/LICENSE');
+  copyFile('./README.md', './dist/README.md');
+  writeFile('./dist/package.json', buildPackageJSON());
+
+  const srcFiles = readdirRecursive('./src', { ignoreDir: /^__.*__$/ });
+  for (const filepath of srcFiles) {
+    if (filepath.endsWith('.js')) {
+      buildJSFile(filepath);
+    }
+  }
+}
+
+function buildJSFile(filepath) {
+  const srcPath = path.join('./src', filepath);
+  const destPath = path.join('./dist', filepath);
+  const cjs = babel.transformFileSync(srcPath, { envName: 'cjs' });
+  const mjs = babel.transformFileSync(srcPath, { envName: 'mjs' });
+
+  copyFile(srcPath, destPath + '.flow');
+  writeFile(destPath, cjs.code);
+  writeFile(destPath.replace(/\.js$/, '.mjs'), mjs.code);
+}
+
+function buildPackageJSON() {
+  const packageJSON = require('../package.json');
+  delete packageJSON.scripts;
+  delete packageJSON.devDependencies;
+
+  const { version } = packageJSON;
+  const match = /^[0-9]+\.[0-9]+\.[0-9]+-?([^.]*)/.exec(version);
+  assert(match, 'Version does not match semver spec.');
+  const tag = match[1];
+  assert(!tag || tag === 'rc', 'Only "rc" tag is supported.');
+
+  assert(!packageJSON.publishConfig, 'Can not override "publishConfig".');
+  packageJSON.publishConfig = { tag: tag || 'latest' };
+  return JSON.stringify(packageJSON, null, 2);
+}

resources/fs-utils.js

@@ -0,0 +1,65 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @noflow
+ */
+
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+
+function mkdirRecursive(path) {
+  fs.mkdirSync(path, { recursive: true });
+}
+
+function rmdirRecursive(dirPath) {
+  if (fs.existsSync(dirPath)) {
+    for (const dirent of fs.readdirSync(dirPath, { withFileTypes: true })) {
+      const fullPath = path.join(dirPath, dirent.name);
+      if (dirent.isDirectory()) {
+        rmdirRecursive(fullPath);
+      } else {
+        fs.unlinkSync(fullPath);
+      }
+    }
+    fs.rmdirSync(dirPath);
+  }
+}
+
+function readdirRecursive(dirPath, opts = {}) {
+  const { ignoreDir } = opts;
+  return fs.readdirSync(dirPath, { withFileTypes: true })
+    .flatMap(dirent => {
+      const name = dirent.name;
+      if (dirent.isDirectory()) {
+        if (ignoreDir && ignoreDir.test(name)) {
+          return [];
+        }
+        return readdirRecursive(path.join(dirPath, name), opts)
+          .map(f => path.join(name, f));
+      }
+      return dirent.name;
+    });
+}
+
+function writeFile(destPath, data) {
+  mkdirRecursive(path.dirname(destPath));
+  fs.writeFileSync(destPath, data);
+}
+
+function copyFile(srcPath, destPath) {
+  mkdirRecursive(path.dirname(destPath));
+  fs.copyFileSync(srcPath, destPath);
+}
+
+module.exports = {
+  copyFile,
+  writeFile,
+  rmdirRecursive,
+  mkdirRecursive,
+  readdirRecursive,
+};