Generate Node.js build in two stages

This proved necessary in order to preserve all aliases in the new
Node.js 12+ ESM entry point.

.gitignore

@@ -11,3 +11,4 @@ cjs
 /underscore.js
 /underscore-min.js
 /underscore-min.js.map
+/underscore-node-*-pre*

package.json

@@ -73,7 +73,7 @@
     "lint": "eslint modules/*.js test/*.js",
     "test-node": "npm run prepare-tests && qunit test/",
     "test-browser": "npm run prepare-tests && npm i karma-phantomjs-launcher && karma start",
-    "bundle": "rollup --config && eslint underscore-umd.js",
+    "bundle": "rollup -c && eslint underscore-umd.js && rollup -c rollup.config2.js",
     "bundle-treeshake": "cd test-treeshake && rollup --config",
     "prepare-tests": "npm run bundle && npm run bundle-treeshake",
     "minify-umd": "terser underscore-umd.js -c \"evaluate=false\" --comments \"/    .*/\" -m",

rollup.common.js

@@ -0,0 +1,27 @@
+import { readFileSync } from 'fs';
+import { extend } from './underscore-esm.js';
+
+var intro = readFileSync('modules/index.js', 'utf-8').split('\n').slice(3, 7).join('\n');
+
+var outputBase = {
+  strict: false,
+  externalLiveBindings: false,
+  freeze: false,
+};
+
+var sourcemapBase = {
+  sourcemap: true,
+  sourcemapExcludeSources: true,
+};
+
+export function outputConf(particular) {
+  return extend(particular, outputBase);
+}
+
+export function sourcemapConf(particular) {
+  return extend(particular, outputBase, sourcemapBase);
+}
+
+export function monolithConf(particular) {
+  return extend(particular, outputBase, sourcemapBase, {intro});
+}

rollup.config.js

@@ -1,33 +1,6 @@
-import { resolve } from 'path';
-import { readFileSync } from 'fs';
-import { extend, filter } from './underscore-esm.js';
 import glob from 'glob';
-
-var intro = readFileSync('modules/index.js', 'utf-8').split('\n').slice(3, 7).join('\n');
-
-var outputBase = {
-  strict: false,
-  externalLiveBindings: false,
-  freeze: false,
-};
-
-var monolithicBase = {
-  intro,
-  sourcemap: true,
-  sourcemapExcludeSources: true,
-};
-
-function outputConf(particular) {
-  return extend(particular, outputBase);
-}
-
-function monolithConf(particular) {
-  return extend(particular, outputBase, monolithicBase);
-}
-
-function resolveModule(id) {
-  return resolve(__dirname, 'modules', id);
-}
+import { filter } from './underscore-esm.js';
+import { outputConf, sourcemapConf, monolithConf } from './rollup.common.js';
 
 export default [
   // Monolithic ESM bundle for browsers and deno.
@@ -54,33 +27,18 @@ export default [
       noConflict: true,
     }),
   },
-  // Custom CJS build for new Node.js.
+  // Custom builds for Node.js, first pass. Second pass in rollup.config2.js.
   {
-    input: 'modules/index-default.js',
+    input: {
+      'underscore-node-cjs-pre': 'modules/index-default.js',
+      'underscore-node-mjs-pre': 'modules/index-all.js',
+    },
     treeshake: false,
-    output: monolithConf({
-      entryFileNames: 'underscore-node.cjs',
-      chunkFileNames: 'underscore-node-[name].cjs',
+    output: sourcemapConf({
+      chunkFileNames: 'underscore-node-f-pre.js',
       dir: '.',
       minifyInternalExports: false,
-      exports: 'auto',
-      format: 'cjs',
-      manualChunks: function(path) {
-        if (!path.match(/index(-default)?\.js$/)) return 'f';
-      },
-    }),
-  },
-  // Custom ESM build for new Node.js. Thin layer on top of CJS build.
-  {
-    input: 'modules/index-all.js',
-    external: ['./index.js', './index-default.js'],
-    output: monolithConf({
-      file: 'underscore-node.mjs',
       format: 'esm',
-      paths: {
-        [resolveModule('index.js')]: './underscore-node-f.cjs',
-        [resolveModule('index-default.js')]: './underscore-node.cjs',
-      },
     }),
   },
   // AMD and CJS versions of the individual modules for development

rollup.config2.js

@@ -0,0 +1,34 @@
+import { resolve } from 'path';
+import { monolithConf } from './rollup.common.js';
+
+var sharedInput = './underscore-node-f-pre.js';
+var sharedOutput = './underscore-node-f.cjs';
+
+export default [
+  // ESM entry point for Node.js 12+.
+  {
+    input: 'underscore-node-mjs-pre.js',
+    external: sharedInput,
+    output: monolithConf({
+      file: 'underscore-node.mjs',
+      format: 'esm',
+      paths: {
+        [resolve(__dirname, sharedInput)]: sharedOutput,
+      },
+    }),
+  },
+  // CJS entry point for Node.js 12+, plus code shared with the ESM entry.
+  {
+    input: {
+      'underscore-node-f': sharedInput,
+      'underscore-node': 'underscore-node-cjs-pre.js',
+    },
+    preserveModules: true,
+    output: monolithConf({
+      entryFileNames: '[name].cjs',
+      dir: '.',
+      exports: 'auto',
+      format: 'cjs',
+    }),
+  },
+];