perf(core): add option to remove blank text nodes from compiled templates (#18823)

PR Close #18823

packages/compiler-cli/src/codegen.ts

@@ -104,6 +104,7 @@ export class CodeGenerator {
       locale: cliOptions.locale, missingTranslation,
       enableLegacyTemplate: options.enableLegacyTemplate !== false,
       enableSummariesForJit: options.enableSummariesForJit !== false,
+      preserveWhitespaces: options.preserveWhitespaces,
     });
     return new CodeGenerator(options, program, tsCompilerHost, aotCompiler, ngCompilerHost);
   }

packages/compiler-cli/src/transformers/api.ts

@@ -91,6 +91,10 @@ export interface CompilerOptions extends ts.CompilerOptions {
 
   // Whether to enable support for <template> and the template attribute (true by default)
   enableLegacyTemplate?: boolean;
+
+  // Whether to remove blank text nodes from compiled templates. It is `true` by default
+  // in Angular 4 and will be re-visited post Angular 5.
+  preserveWhitespaces?: boolean;
 }
 
 export interface ModuleFilenameResolver {

packages/compiler-cli/src/transformers/program.ts

@@ -388,4 +388,4 @@ function createProgramWithStubsHost(
     fileExists = (fileName: string) =>
         this.generatedFiles.has(fileName) || originalHost.fileExists(fileName);
   };
-}
+}