do not add mappings for empty/comment lines (fix module.exports source map bug)

Author: yyx990803

lib/loader.js

@@ -14,7 +14,7 @@ var defaultLang = {
 var defaultLoaders = {
   html: 'vue-html-loader',
   css: 'vue-style-loader!css-loader',
-  js: 'babel-loader?presets[]=es2015&plugins[]=transform-runtime'
+  js: 'babel-loader?presets[]=es2015&plugins[]=transform-runtime&comments=false'
 }
 
 var rewriterInjectRE = /\b((css|(vue-)?html)(-loader)?(\?[^!]+)?!?)\b/

lib/parser.js

@@ -106,18 +106,27 @@ module.exports = function (content, filename, needMap) {
       // generate source map
       map = new SourceMapGenerator()
       map.setSourceContent(filenameWithHash, content)
+
+      // do not add mappings for comment lines - babel's source map
+      // somehow gets messed up because of it
+      var isCommentLine = function (line) {
+        return type === 'script' && !lang && line.indexOf('//') === 0
+      }
+
       result.split(splitRE).forEach(function (line, index) {
-        map.addMapping({
-          source: filenameWithHash,
-          original: {
-            line: index + 1 + lineOffset,
-            column: 0
-          },
-          generated: {
-            line: index + 1,
-            column: 0
-          }
-        })
+        if (!emptyRE.test(line) && !isCommentLine(line)) {
+          map.addMapping({
+            source: filenameWithHash,
+            original: {
+              line: index + 1 + lineOffset,
+              column: 0
+            },
+            generated: {
+              line: index + 1,
+              column: 0
+            }
+          })
+        }
       })
       // workaround for Webpack eval-source-map bug
       // https://github.com/webpack/webpack/pull/1816
@@ -145,19 +154,17 @@ function commentScript (content, lang) {
   return content
     .split(splitRE)
     .map(function (line) {
-      if (emptyRE.test(line)) {
-        return line
-      }
+      line = emptyRE.test(line) ? '' : ' ' + line
       switch (lang) {
         case 'coffee':
         case 'coffee-jsx':
         case 'coffee-redux':
-          return '# ' + line
+          return '#' + line
         case 'purs':
         case 'ulmus':
-          return '-- ' + line
+          return '--' + line
         default:
-          return '// ' + line
+          return '//' + line
       }
     })
     .join('\n')

test/fixtures/basic.vue

@@ -1,19 +1,19 @@
-<style>
-comp-a h2 {
-  color: #f00;
-}
-</style>
-
 <template>
   <h2 class="red">{{msg}}</h2>
 </template>
 
 <script>
-export default {
+module.exports = {
   data () {
     return {
       msg: 'Hello from Component A!'
     }
   }
 }
 </script>
+
+<style>
+comp-a h2 {
+  color: #f00;
+}
+</style>

test/test.js

@@ -165,7 +165,7 @@ describe('vue-loader', function () {
             column: col
           })
           expect(pos.source.indexOf('basic.vue') > -1)
-          expect(pos.line).to.equal(15)
+          expect(pos.line).to.equal(9)
           done()
         })
       })