feat: add --pkg-main option (#658)

Author: katywings

README.md

@@ -178,6 +178,14 @@ Microbundle uses the fields from your `package.json` to figure out where it shou
 }
 ```
 
+### Building a single bundle with a fixed output name
+
+By default Microbundle outputs multiple bundles, one bundle per format. A single bundle with a fixed output name can be built like this:
+
+```bash
+microbundle -i lib/main.js -o dist/bundle.js --no-pkg-main -f umd
+```
+
 ### Mangling Properties
 
 To achieve the smallest possible bundle size, libraries often wish to rename internal object properties or class members to smaller names - transforming `this._internalIdValue` to `this._i`. Microbundle doesn't do this by default, however it can be enabled by creating a `mangle.json` file (or a `"mangle"` property in your package.json). Within that file, you can specify a regular expression pattern to control which properties should be mangled. For example: to mangle all property names beginning an underscore:
@@ -212,6 +220,7 @@ Options
 	-o, --output     Directory to place build files into
 	-f, --format     Only build specified formats (any of modern,es,cjs,umd or iife) (default modern,es,cjs,umd)
 	-w, --watch      Rebuilds on any change  (default false)
+	--pkg-main       Outputs files analog to package.json main entries  (default true)
 	--target         Specify your target environment (node or web)  (default web)
 	--external       Specify external dependencies, or 'none' (default peerDependencies and dependencies in package.json)
 	--globals        Specify globals dependencies, or 'none'

src/index.js

@@ -392,6 +392,54 @@ async function getEntries({ input, cwd }) {
 	return entries;
 }
 
+function replaceName(filename, name) {
+	return resolve(
+		dirname(filename),
+		name + basename(filename).replace(/^[^.]+/, ''),
+	);
+}
+
+function getMain({ options, entry, format }) {
+	const { pkg } = options;
+	const pkgMain = options['pkg-main'];
+
+	if (!pkgMain) {
+		return options.output;
+	}
+
+	let mainNoExtension = options.output;
+	if (options.multipleEntries) {
+		let name = entry.match(/([\\/])index(\.(umd|cjs|es|m))?\.(mjs|[tj]sx?)$/)
+			? mainNoExtension
+			: entry;
+		mainNoExtension = resolve(dirname(mainNoExtension), basename(name));
+	}
+	mainNoExtension = mainNoExtension.replace(
+		/(\.(umd|cjs|es|m))?\.(mjs|[tj]sx?)$/,
+		'',
+	);
+
+	const mainsByFormat = {};
+
+	mainsByFormat.es = replaceName(
+		pkg.module && !pkg.module.match(/src\//)
+			? pkg.module
+			: pkg['jsnext:main'] || 'x.esm.js',
+		mainNoExtension,
+	);
+	mainsByFormat.modern = replaceName(
+		(pkg.syntax && pkg.syntax.esmodules) || pkg.esmodule || 'x.modern.js',
+		mainNoExtension,
+	);
+	mainsByFormat.cjs = replaceName(pkg['cjs:main'] || 'x.js', mainNoExtension);
+	mainsByFormat.umd = replaceName(
+		pkg['umd:main'] || 'x.umd.js',
+		mainNoExtension,
+	);
+
+	return mainsByFormat[format] || mainsByFormat.cjs;
+}
+
 // shebang cache map because the transform only gets run once
 const shebang = {};
 
@@ -442,38 +490,6 @@ function createConfig(options, entry, format, writeMeta) {
 		);
 	}
 
-	function replaceName(filename, name) {
-		return resolve(
-			dirname(filename),
-			name + basename(filename).replace(/^[^.]+/, ''),
-		);
-	}
-
-	let mainNoExtension = options.output;
-	if (options.multipleEntries) {
-		let name = entry.match(/([\\/])index(\.(umd|cjs|es|m))?\.(mjs|[tj]sx?)$/)
-			? mainNoExtension
-			: entry;
-		mainNoExtension = resolve(dirname(mainNoExtension), basename(name));
-	}
-	mainNoExtension = mainNoExtension.replace(
-		/(\.(umd|cjs|es|m))?\.(mjs|[tj]sx?)$/,
-		'',
-	);
-
-	let moduleMain = replaceName(
-		pkg.module && !pkg.module.match(/src\//)
-			? pkg.module
-			: pkg['jsnext:main'] || 'x.esm.js',
-		mainNoExtension,
-	);
-	let modernMain = replaceName(
-		(pkg.syntax && pkg.syntax.esmodules) || pkg.esmodule || 'x.modern.js',
-		mainNoExtension,
-	);
-	let cjsMain = replaceName(pkg['cjs:main'] || 'x.js', mainNoExtension);
-	let umdMain = replaceName(pkg['umd:main'] || 'x.umd.js', mainNoExtension);
-
 	const modern = format === 'modern';
 
 	// let rollupName = safeVariableName(basename(entry).replace(/\.js$/, ''));
@@ -698,14 +714,7 @@ function createConfig(options, entry, format, writeMeta) {
 			},
 			format: modern ? 'es' : format,
 			name: options.name,
-			file: resolve(
-				options.cwd,
-				{
-					modern: modernMain,
-					es: moduleMain,
-					umd: umdMain,
-				}[format] || cjsMain,
-			),
+			file: resolve(options.cwd, getMain({ options, entry, format })),
 		},
 	};
 

src/prog.js

@@ -28,6 +28,11 @@ export default handler => {
 			DEFAULT_FORMATS,
 		)
 		.option('--watch, -w', 'Rebuilds on any change', false)
+		.option(
+			'--pkg-main',
+			'Outputs files analog to package.json main entries',
+			true,
+		)
 		.option('--target', 'Specify your target environment (node or web)', 'web')
 		.option('--external', `Specify external dependencies, or 'none'`)
 		.option('--globals', `Specify globals dependencies, or 'none'`)

test/__snapshots__/index.test.js.snap

@@ -731,6 +731,38 @@ exports[`fixtures build basic-no-compress with microbundle 5`] = `
 "
 `;
 
+exports[`fixtures build basic-no-pkg-main with microbundle 1`] = `
+"Used script: microbundle --pkg-main false
+
+Directory tree:
+
+basic-no-pkg-main
+  dist
+    basic-no-pkg-main.js
+    basic-no-pkg-main.js.map
+  package.json
+  src
+    index.js
+    two.js
+
+
+Build \\"basicNoPkgMain\\" to dist:
+187 B: basic-no-pkg-main.js.gz
+138 B: basic-no-pkg-main.js.br
+188 B: basic-no-pkg-main.js.gz
+139 B: basic-no-pkg-main.js.br
+279 B: basic-no-pkg-main.js.gz
+229 B: basic-no-pkg-main.js.br"
+`;
+
+exports[`fixtures build basic-no-pkg-main with microbundle 2`] = `2`;
+
+exports[`fixtures build basic-no-pkg-main with microbundle 3`] = `
+"!function(e,r){\\"object\\"==typeof exports&&\\"undefined\\"!=typeof module?module.exports=r():\\"function\\"==typeof define&&define.amd?define(r):(e=e||self).basicNoPkgMain=r()}(this,function(){var e=function(){try{var e=arguments;return Promise.resolve([].slice.call(e).reduce(function(e,r){return e+r},0))}catch(e){return Promise.reject(e)}};return function(){try{var r=arguments,n=[].slice.call(r);return Promise.resolve(e.apply(void 0,n)).then(function(r){return Promise.resolve(e.apply(void 0,n)).then(function(e){return[r,e]})})}catch(e){return Promise.reject(e)}}});
+//# sourceMappingURL=basic-no-pkg-main.js.map
+"
+`;
+
 exports[`fixtures build basic-ts with microbundle 1`] = `
 "Used script: microbundle
 

test/fixtures/basic-no-pkg-main/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "basic-no-pkg-main",
+  "scripts": {
+    "build": "microbundle --pkg-main false"
+  }
+}

test/fixtures/basic-no-pkg-main/src/index.js

@@ -0,0 +1,5 @@
+import { two } from './two';
+
+export default async function(...args) {
+	return [await two(...args), await two(...args)];
+}

test/fixtures/basic-no-pkg-main/src/two.js

@@ -0,0 +1,3 @@
+export async function two(...args) {
+	return args.reduce((total, value) => total + value, 0);
+}