Build system: add option to generate source maps for production builds (

prebid#8220)

gulpfile.js

@@ -134,7 +134,9 @@ function makeDevpackPkg() {
 
 function makeWebpackPkg() {
   var cloned = _.cloneDeep(webpackConfig);
-  delete cloned.devtool;
+  if (!argv.sourceMaps) {
+    delete cloned.devtool;
+  }
 
   var externalModules = helpers.getArgModules();
 
@@ -144,10 +146,19 @@ function makeWebpackPkg() {
   return gulp.src([].concat(moduleSources, analyticsSources, 'src/prebid.js'))
     .pipe(helpers.nameModules(externalModules))
     .pipe(webpackStream(cloned, webpack))
-    .pipe(gulpif(file => file.basename === 'prebid-core.js', header(banner, { prebid: prebid })))
     .pipe(gulp.dest('build/dist'));
 }
 
+function addBanner() {
+  const sm = argv.sourceMaps;
+
+  return gulp.src(['build/dist/prebid-core.js'])
+    .pipe(gulpif(sm, sourcemaps.init({loadMaps: true})))
+    .pipe(header(banner, {prebid}))
+    .pipe(gulpif(sm, sourcemaps.write('.')))
+    .pipe(gulp.dest('build/dist'))
+}
+
 function getModulesListToAddInBanner(modules) {
   return (modules.length > 0) ? modules.join(', ') : 'All available modules in current version.';
 }
@@ -172,6 +183,7 @@ function nodeBundle(modules) {
 function bundle(dev, moduleArr) {
   var modules = moduleArr || helpers.getArgModules();
   var allModules = helpers.getModuleNames(modules);
+  const sm = dev || argv.sourceMaps;
 
   if (modules.length === 0) {
     modules = allModules.filter(module => explicitModules.indexOf(module) === -1);
@@ -203,13 +215,13 @@ function bundle(dev, moduleArr) {
   )
     // Need to uodate the "Modules: ..." section in comment with the current modules list
     .pipe(replace(/(Modules: )(.*?)(\*\/)/, ('$1' + getModulesListToAddInBanner(helpers.getArgModules()) + ' $3')))
-    .pipe(gulpif(dev, sourcemaps.init({ loadMaps: true })))
+    .pipe(gulpif(sm, sourcemaps.init({ loadMaps: true })))
     .pipe(concat(outputFileName))
     .pipe(gulpif(!argv.manualEnable, footer('\n<%= global %>.processQueue();', {
       global: prebid.globalVarName
     }
     )))
-    .pipe(gulpif(dev, sourcemaps.write('.')));
+    .pipe(gulpif(sm, sourcemaps.write('.')));
 }
 
 // Run the unit tests.
@@ -398,7 +410,7 @@ gulp.task(clean);
 gulp.task(escapePostbidConfig);
 
 gulp.task('build-bundle-dev', gulp.series(makeDevpackPkg, gulpBundle.bind(null, true)));
-gulp.task('build-bundle-prod', gulp.series(makeWebpackPkg, gulpBundle.bind(null, false)));
+gulp.task('build-bundle-prod', gulp.series(makeWebpackPkg, addBanner, gulpBundle.bind(null, false)));
 
 // public tasks (dependencies are needed for each task since they can be ran on their own)
 gulp.task('test-only', test);
@@ -417,7 +429,7 @@ gulp.task('serve-fast', gulp.series(clean, gulp.parallel('build-bundle-dev', wat
 gulp.task('serve-and-test', gulp.series(clean, gulp.parallel('build-bundle-dev', watchFast, testTaskMaker({watch: true}))));
 gulp.task('serve-fake', gulp.series(clean, gulp.parallel('build-bundle-dev', watch), injectFakeServerEndpointDev, test, startFakeServer));
 
-gulp.task('default', gulp.series(clean, makeWebpackPkg));
+gulp.task('default', gulp.series(clean, 'build-bundle-prod'));
 
 gulp.task('e2e-test', gulp.series(clean, setupE2e, gulp.parallel('build-bundle-prod', watch), injectFakeServerEndpoint, test));
 // other tasks