Further improvements to how paths for output files are generated in u…

…nbundled mode

lib/BundleMappings.js

@@ -184,10 +184,33 @@ BundleMappings.prototype = {
             bundle.dependency = dependency;
             bundle.isExternalResource = true;
         } else if (this.bundlingEnabled === false) {
+            // Bundling is NOT enabled
+
+            // We will try to find a relative path that will be used for
+            // the output file of the bundle.
+            // This relative path might be different from the bundle name
+            // if a defaultBundleName is provided
+            //
+            // NOTE: If we don't have a defaultBundleName for this dependency
+            // and if we don't find a relative path then we will use
+            // `${dependencyType}-${pageBundleName}` as the
+            // bundle name.
+
             var sourceFile;
             var relPath;
 
+            var unbundledTargetPrefix;
+
+            if (dependency.getUnbundledTargetPrefix) {
+                // The unbundled target prefix adds a common prefix to the beginning of
+                // relative paths for all output files
+                unbundledTargetPrefix = dependency.getUnbundledTargetPrefix(lassoContext);
+            }
+
             if (dependency.getUnbundledTarget) {
+                // The dependency provides a getUnbundledTarget(lassoContext)
+                // so we will try to use that determine a relative path
+                // which will be used as the bundle name
                 sourceFile = dependency.getUnbundledTarget(lassoContext) + '-' + pageBundleName.replace(/[\\\/]/g, '-');
             }
 
@@ -200,8 +223,16 @@ BundleMappings.prototype = {
                 var projectRoot = this.config.getProjectRoot();
 
                 if (sourceFile.startsWith(projectRoot + fileSep)) {
+                    // source file is within the project root directory
+                    // so let's remove the project root directory
+                    // path from the source file path which will
+                    // leave us with a relative path
                     relPath = sourceFile.substring(projectRoot.length);
                 } else {
+                    // source file seems to be outside the project root
+                    // directory so we will see if we can resolve
+                    // the module associated with the source file and
+                    // use that build an appropriate relative path
                     var dirname = nodePath.dirname(sourceFile);
                     if (dirname) {
                         var modulePkg = tryGetModuleRootPackage(dirname);
@@ -221,6 +252,12 @@ BundleMappings.prototype = {
                 relPath = sourceFile;
             }
 
+            if (unbundledTargetPrefix) {
+                // If an unbundledTargetPrefix is provided then add that
+                // to the start of the relative path.
+                relPath = nodePath.join(unbundledTargetPrefix, relPath);
+            }
+
             bundle = this.addDependencyToBundle(
                 dependency,
                 dependency.defaultBundleName || relPath || (dependency.type + '-' + pageBundleName),
@@ -230,9 +267,12 @@ BundleMappings.prototype = {
 
             // bundle.dependency = dependency;
             if (relPath) {
+                // We associate this bundle with a relative path which will
+                // be used as the output file for the bundle
                 bundle.relativeOutputPath = relPath;
             }
         } else {
+            // Bundling is enabled
             //Make sure the dependency is part of a bundle. If it not part of a preconfigured bundle then put it in a page-specific bundle
             bundle = this.addDependencyToBundle(
                 dependency,