New mainfields option

README.md

@@ -25,24 +25,33 @@ export default {
   },
   plugins: [
     resolve({
+
+      // the fields to scan in a package.json to determine the entry point
+      // if this list contains "browser", overrides specified in "pkg.browser"
+      // will be used
+      mainFields: ['module', 'main'], // Default: ['module', 'main']
+
+      // DEPRECATED: use "mainFields" instead
       // use "module" field for ES6 module if possible
       module: true, // Default: true
 
+      // DEPRECATED: use "mainFields" instead
       // use "jsnext:main" if possible
       // legacy field pointing to ES6 module in third-party libraries,
       // deprecated in favor of "pkg.module":
       // - see: https://github.com/rollup/rollup/wiki/pkg.module
       jsnext: true,  // Default: false
 
+      // DEPRECATED: use "mainFields" instead
       // use "main" field or index.js, even if it's not an ES6 module
       // (needs to be converted from CommonJS to ES6)
       // – see https://github.com/rollup/rollup-plugin-commonjs
       main: true,  // Default: true
 
-      // some package.json files have a `browser` field which
-      // specifies alternative files to load for people bundling
-      // for the browser. If that's you, use this option, otherwise
-      // pkg.browser will be ignored
+      // some package.json files have a "browser" field which specifies
+      // alternative files to load for people bundling for the browser. If
+      // that's you, either use this option or add "browser" to the
+      // "mainfields" option, otherwise pkg.browser will be ignored
       browser: true,  // Default: false
 
       // not all files you want to resolve are .js files

index.d.ts

@@ -1,13 +1,22 @@
-import { Plugin } from 'rollup';
-import { AsyncOpts } from 'resolve';
+import {Plugin} from 'rollup';
+import {AsyncOpts} from 'resolve';
 
 interface RollupNodeResolveOptions {
 	/**
+	 * the fields to scan in a package.json to determine the entry point
+	 * if this list contains "browser", overrides specified in "pkg.browser"
+	 * will be used
+	 * @default ['module', 'main']
+	 */
+	mainFields?: ['browser', 'esnext', 'module', 'main'],
+	/**
+	 * @deprecated use "mainFields" instead
 	 * use "module" field for ES6 module if possible
 	 * @default true
 	 */
 	module?: boolean;
 	/**
+	 * @deprecated use "mainFields" instead
 	 * use "jsnext:main" if possible
 	 * legacy field pointing to ES6 module in third-party libraries,
 	 * deprecated in favor of "pkg.module":
@@ -16,17 +25,18 @@ interface RollupNodeResolveOptions {
 	 */
 	jsnext?: boolean;
 	/**
+	 * @deprecated use "mainFields" instead
 	 * use "main" field or index.js, even if it's not an ES6 module
 	 * (needs to be converted from CommonJS to ES6)
 	 * – see https://github.com/rollup/rollup-plugin-commonjs
 	 * @default true
 	 */
 	main?: boolean;
 	/**
-	 * some package.json files have a `browser` field which
-	 * specifies alternative files to load for people bundling
-	 * for the browser. If that's you, use this option, otherwise
-	 * pkg.browser will be ignored
+	 * some package.json files have a "browser" field which specifies
+	 * alternative files to load for people bundling for the browser. If
+	 * that's you, either use this option or add "browser" to the
+	 * "mainfields" option, otherwise pkg.browser will be ignored
 	 * @default false
 	 */
 	browser?: boolean;

src/index.js

@@ -37,12 +37,41 @@ function cachedIsFile (file, cb) {
 	isFileCache[file].then(contents => cb(null, contents), cb);
 }
 
+function getMainFields (options) {
+	let mainFields;
+	if (options.mainFields) {
+		if ('module' in options || 'main' in options || 'jsnext' in options) {
+			throw new Error(`node-resolve: do not use deprecated 'module', 'main', 'jsnext' options with 'mainFields'`);
+		}
+		mainFields = options.mainFields;
+	} else {
+		mainFields = ['module', 'main'];
+		[['module', 'module'], ['jsnext', 'jsnext:main'], ['main', 'main']].forEach(([option, field]) => {
+			if (option in options) {
+				// eslint-disable-next-line no-console
+				console.warn(`node-resolve: setting options.${option} is deprecated, please override options.mainFields instead`);
+				if (options[option] === false) {
+					mainFields = mainFields.filter(mainField => mainField === field);
+				} else if (options[option] === true && mainFields.indexOf(field) === -1) {
+					mainFields.push(field);
+				}
+			}
+		});
+	}
+	if (options.browser && mainFields.indexOf('browser') === -1) {
+		return ['browser'].concat(mainFields);
+	}
+	if ( !mainFields.length ) {
+		throw new Error( `Please ensure at least one 'mainFields' value is specified` );
+	}
+	return mainFields;
+}
+
 const resolveIdAsync = (file, opts) => new Promise((fulfil, reject) => resolveId(file, opts, (err, contents) => err ? reject(err) : fulfil(contents)));
 
 export default function nodeResolve ( options = {} ) {
-	const useModule = options.module !== false;
-	const useMain = options.main !== false;
-	const useJsnext = options.jsnext === true;
+	const mainFields = getMainFields(options);
+	const useBrowserOverrides = mainFields.indexOf('browser') !== -1;
 	const isPreferBuiltinsSet = options.preferBuiltins === true || options.preferBuiltins === false;
 	const preferBuiltins = isPreferBuiltinsSet ? options.preferBuiltins : true;
 	const customResolveOptions = options.customResolveOptions || {};
@@ -59,10 +88,6 @@ export default function nodeResolve ( options = {} ) {
 		throw new Error( 'options.skip is no longer supported — you should use the main Rollup `external` option instead' );
 	}
 
-	if ( !useModule && !useMain && !useJsnext ) {
-		throw new Error( `At least one of options.module, options.main or options.jsnext must be true` );
-	}
-
 	let preserveSymlinks;
 
 	return {
@@ -83,7 +108,7 @@ export default function nodeResolve ( options = {} ) {
 			const basedir = importer ? dirname( importer ) : process.cwd();
 
 			// https://github.com/defunctzombie/package-browser-field-spec
-			if (options.browser && browserMapCache[importer]) {
+			if (useBrowserOverrides && browserMapCache[importer]) {
 				const resolvedImportee = resolve( basedir, importee );
 				const browser = browserMapCache[importer];
 				if (browser[importee] === false || browser[resolvedImportee] === false) {
@@ -115,7 +140,7 @@ export default function nodeResolve ( options = {} ) {
 				basedir,
 				packageFilter ( pkg, pkgPath ) {
 					const pkgRoot = dirname( pkgPath );
-					if (options.browser && typeof pkg[ 'browser' ] === 'object') {
+					if (useBrowserOverrides && typeof pkg[ 'browser' ] === 'object') {
 						packageBrowserField = Object.keys(pkg[ 'browser' ]).reduce((browser, key) => {
 							let resolved = pkg[ 'browser' ][ key ];
 							if (resolved && resolved[0] === '.') {
@@ -136,13 +161,16 @@ export default function nodeResolve ( options = {} ) {
 						}, {});
 					}
 
-					if (options.browser && typeof pkg[ 'browser' ] === 'string') {
-						pkg[ 'main' ] = pkg[ 'browser' ];
-					} else if ( useModule && pkg[ 'module' ] ) {
-						pkg[ 'main' ] = pkg[ 'module' ];
-					} else if ( useJsnext && pkg[ 'jsnext:main' ] ) {
-						pkg[ 'main' ] = pkg[ 'jsnext:main' ];
-					} else if ( ( useJsnext || useModule ) && !useMain ) {
+					let overriddenMain = false;
+					for ( let i = 0; i < mainFields.length; i++ ) {
+						const field = mainFields[i];
+						if ( typeof pkg[ field ] === 'string' ) {
+							pkg[ 'main' ] = pkg[ field ];
+							overriddenMain = true;
+							break;
+						}
+					}
+					if ( overriddenMain === false && mainFields.indexOf( 'main' ) === -1 ) {
 						disregardResult = true;
 					}
 					return pkg;
@@ -161,7 +189,7 @@ export default function nodeResolve ( options = {} ) {
 				Object.assign( resolveOptions, customResolveOptions )
 			)
 				.then(resolved => {
-					if ( resolved && options.browser && packageBrowserField ) {
+					if ( resolved && useBrowserOverrides && packageBrowserField ) {
 						if ( packageBrowserField.hasOwnProperty(resolved) ) {
 							if (!packageBrowserField[resolved]) {
 								browserMapCache[resolved] = packageBrowserField;