feat(bundler): support npm package shipped in native es module

Although Nodejs doesn't support es module by default, webpack supports it. Some npm packages like bpmn-js are shipped in native es module format. They are consumable by webpack but not Nodejs. This feature closes the gap between our built-in bundler and webpack.

closes #872

lib/build/amodro-trace/read/cjs.js

@@ -14,32 +14,23 @@ var parse = require('../lib/parse');
 // https://github.com/requirejs/r.js/issues/980
 module.exports = function cjs(fileName, fileContents, forceWrap) {
   // Strip out comments.
-  try {
-    var preamble = '',
-    commonJsProps = parse.usesCommonJs(fileName, fileContents);
+  var preamble = '',
+  commonJsProps = parse.usesCommonJs(fileName, fileContents);
 
-    // First see if the module is not already RequireJS-formatted.
-    if (!forceWrap && (parse.usesAmdOrRequireJs(fileName, fileContents) || !commonJsProps)) {
-      return fileContents;
-    }
-
-    if (commonJsProps && (commonJsProps.dirname || commonJsProps.filename)) {
-      preamble = 'var __filename = module.uri || \'\', ' +
-        '__dirname = ' +
-        '__filename.substring(0, __filename.lastIndexOf(\'/\') + 1); ';
-    }
-
-    // Construct the wrapper boilerplate.
-    fileContents = 'define(function (require, exports, module) {' +
-    preamble +
-    fileContents +
-    '\n});\n';
-
-  } catch (e) {
-    console.log('commonJs.convert: COULD NOT CONVERT: ' + fileName +
-          ', so skipping it. Error was: ' + e);
+  // First see if the module is not already RequireJS-formatted.
+  if (!forceWrap && (parse.usesAmdOrRequireJs(fileName, fileContents) || !commonJsProps)) {
     return fileContents;
   }
 
-  return fileContents;
+  if (commonJsProps && (commonJsProps.dirname || commonJsProps.filename)) {
+    preamble = 'var __filename = module.uri || \'\', ' +
+      '__dirname = ' +
+      '__filename.substring(0, __filename.lastIndexOf(\'/\') + 1); ';
+  }
+
+  // Construct the wrapper boilerplate.
+  return 'define(function (require, exports, module) {' +
+  preamble +
+  fileContents +
+  '\n});\n';
 };

lib/build/amodro-trace/read/es.js

@@ -0,0 +1,10 @@
+'use strict';
+const transform = require('babel-core').transform;
+
+// use babel to translate native es module into AMD module
+module.exports = function es(fileName, fileContents) {
+  return transform(fileContents, {
+    babelrc: false,
+    plugins: ['transform-es2015-modules-amd']
+  }).code;
+};

lib/build/bundled-source.js

@@ -2,6 +2,7 @@
 const path = require('path');
 const findDeps = require('./find-deps').findDeps;
 const cjsTransform = require('./amodro-trace/read/cjs');
+const esTransform = require('./amodro-trace/read/es');
 const allWriteTransforms = require('./amodro-trace/write/all');
 const logger = require('aurelia-logging').getLogger('BundledSource');
 
@@ -117,7 +118,21 @@ exports.BundledSource = class {
       // forceCjsWrap bypasses a r.js parse bug.
       // See lib/amodro-trace/read/cjs.js for more info.
       let forceCjsWrap = !!modulePath.match(/\/(cjs|commonjs)\//i);
-      let contents = cjsTransform(modulePath, this.contents, forceCjsWrap);
+      let contents;
+
+      try {
+        contents = cjsTransform(modulePath, this.contents, forceCjsWrap);
+      } catch (ignore) {
+        // file is not in amd/cjs format, try native es module
+        try {
+          contents = esTransform(modulePath, this.contents);
+        } catch (e) {
+          logger.error('Could not convert to AMD module, skipping ' + modulePath);
+          logger.error('Error was: ' + e);
+          contents = this.contents;
+        }
+      }
+
       deps = findDeps(modulePath, contents);
 
       let context = {pkgsMainMap: {}, config: {shim: {}}};

package.json

@@ -33,6 +33,7 @@
     "aurelia-dependency-injection": "^1.0.0",
     "aurelia-logging": "^1.2.0",
     "aurelia-polyfills": "^1.0.0",
+    "babel-plugin-transform-es2015-modules-amd": "^6.24.1",
     "babel-polyfill": "^6.0.0 || ^7.0.0 || ^8.0.0",
     "babel-register": "^6.0.0 || ^7.0.0 || ^8.0.0",
     "esprima": "^4.0.0",

spec/lib/build/bundled-source.spec.js

@@ -202,6 +202,39 @@ exports.t = t;
       .toBe("define('foo/bar/lo',['require','exports','module','./t'],function (require, exports, module) {var t = require('./t');exports.t = t;});");
   });
 
+  it('transforms npm package js file in native es module format', () => {
+    let file = {
+      path: path.resolve(cwd, 'node_modules/foo/bar/lo.js'),
+      contents: `
+import t from './t';
+export {t};
+`
+    };
+
+    let bs = new BundledSource(bundler, file);
+    bs._getProjectRoot = () => 'src';
+    bs.includedBy = {
+      includedBy: {
+        description: {
+          name: 'foo',
+          mainId: 'foo/index',
+          loaderConfig: {
+            name: 'foo',
+            path: '../node_modules/foo',
+            main: 'index'
+          }
+        }
+      }
+    };
+    bs._getLoaderPlugins = () => [];
+    bs._getLoaderConfig = () => ({paths: {}});
+
+    let deps = bs.transform();
+    expect(deps).toEqual(['foo/bar/t']);
+    expect(bs.requiresTransform).toBe(false);
+    // assume babel did right job for bs.contents
+  });
+
   it('transforms npm package js file with named AMD module', () => {
     let file = {
       path: path.resolve(cwd, 'node_modules/foo/index.js'),