feat(core): set preserveWhitespaces to false by default (#22046)

Fixes #22027

PR Close #22046

aio/content/guide/aot-compiler.md

@@ -92,7 +92,7 @@ You can control your app compilation by providing template compiler options in t
   },
   "angularCompilerOptions": {
     "fullTemplateTypeCheck": true,
-    "preserveWhitespaces": false,
+    "preserveWhitespaces": true,
     ...
   }
 }
@@ -234,9 +234,7 @@ done manually.
 ### *preserveWhitespaces*
 
 This option tells the compiler whether to remove blank text nodes from compiled templates.
-This option is `true` by default.
-
-*Note*: It is recommended to set this explicitly to `false` as it emits smaller template factory modules and might be set to `false` by default in the future.
+As of v6, this option is `false` by default, which results in smaller emitted template factory modules.
 
 ### *allowEmptyCodegenFiles*
 

packages/bazel/src/ng_module.bzl

@@ -91,8 +91,7 @@ def _ngc_tsconfig(ctx, files, srcs, **kwargs):
           "enableSummariesForJit": True,
           "fullTemplateTypeCheck": ctx.attr.type_check,
           # FIXME: wrong place to de-dupe
-          "expectedOut": depset([o.path for o in expected_outs]).to_list(),
-          "preserveWhitespaces": False,
+          "expectedOut": depset([o.path for o in expected_outs]).to_list()
       }
   })
 

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

@@ -148,8 +148,8 @@ export interface CompilerOptions extends ts.CompilerOptions {
   // How to handle missing messages
   i18nInMissingTranslations?: 'error'|'warning'|'ignore';
 
-  // Whether to remove blank text nodes from compiled templates. It is `true` by default
-  // in Angular 5 and will be re-visited in Angular 6.
+  // Whether to remove blank text nodes from compiled templates. It is `false` by default starting
+  // from Angular 6.
   preserveWhitespaces?: boolean;
 
   /** generate all possible generated files  */

packages/compiler/src/config.ts

@@ -46,6 +46,6 @@ export class CompilerConfig {
 }
 
 export function preserveWhitespacesDefault(
-    preserveWhitespacesOption: boolean | null, defaultSetting = true): boolean {
+    preserveWhitespacesOption: boolean | null, defaultSetting = false): boolean {
   return preserveWhitespacesOption === null ? defaultSetting : preserveWhitespacesOption;
 }

packages/compiler/test/config_spec.ts

@@ -7,7 +7,7 @@
  */
 
 import {MissingTranslationStrategy} from '@angular/core';
-import {CompilerConfig} from '../src/config';
+import {CompilerConfig, preserveWhitespacesDefault} from '../src/config';
 
 {
   describe('compiler config', () => {
@@ -16,4 +16,13 @@ import {CompilerConfig} from '../src/config';
       expect(config.missingTranslation).toEqual(MissingTranslationStrategy.Error);
     });
   });
+
+  describe('preserveWhitespacesDefault', () => {
+    it('should return the default `false` setting when no preserveWhitespacesOption are provided',
+       () => { expect(preserveWhitespacesDefault(null)).toEqual(false); });
+    it('should return the preserveWhitespacesOption when provided as a parameter', () => {
+      expect(preserveWhitespacesDefault(true)).toEqual(true);
+      expect(preserveWhitespacesDefault(false)).toEqual(false);
+    });
+  });
 }

packages/core/src/metadata/directives.ts

@@ -693,13 +693,13 @@ export interface Component extends Directive {
    * - text nodes are left as-is inside HTML tags where whitespaces are significant (ex. `<pre>`,
    *   `<textarea>`).
    *
-   * Described transformations can (potentially) influence DOM nodes layout so the
-   * `preserveWhitespaces` option is `true` be default (no whitespace removal).
-   * In Angular 5 you need to opt-in for whitespace removal (but we might revisit the default
-   * setting in Angular 6 or later). If you want to change the default setting for all components
-   * in your application you can use the `preserveWhitespaces` option of the AOT compiler.
+   * Described transformations may (potentially) influence DOM nodes layout. However, the impact
+   * should so be minimal. That's why starting from Angular 6, the
+   * `preserveWhitespaces` option is `false` by default (whitespace removal).
+   * If you want to change the default setting for all components in your application you can use
+   * the `preserveWhitespaces` option of the AOT compiler.
    *
-   * Even if you decide to opt-in for whitespace removal there are ways of preserving whitespaces
+   * Even with the default behavior of whitespace removal, there are ways of preserving whitespaces
    * in certain fragments of a template. You can either exclude entire DOM sub-tree by using the
    * `ngPreserveWhitespaces` attribute, ex.:
    *

packages/core/test/debug/debug_node_spec.ts

@@ -191,9 +191,7 @@ class TestApp {
     it('should list all child nodes', () => {
       fixture = TestBed.createComponent(ParentComp);
       fixture.detectChanges();
-
-      // The root component has 3 elements and 2 text node children.
-      expect(fixture.debugElement.childNodes.length).toEqual(5);
+      expect(fixture.debugElement.childNodes.length).toEqual(3);
     });
 
     it('should list all component child elements', () => {

packages/core/test/linker/integration_spec.ts

@@ -1280,7 +1280,7 @@ function declareTests({useJit}: {useJit: boolean}) {
         fixture.detectChanges();
         expect(fixture.nativeElement)
             .toHaveText(
-                'Default Interpolation\nCustom Interpolation A\nCustom Interpolation B (Default Interpolation)');
+                'Default InterpolationCustom Interpolation ACustom Interpolation B (Default Interpolation)');
       });
     });
 
@@ -1792,7 +1792,7 @@ function declareTests({useJit}: {useJit: boolean}) {
            const f = TestBed.configureTestingModule({declarations: [MyCmp]}).createComponent(MyCmp);
            f.detectChanges();
 
-           expect(f.nativeElement.childNodes.length).toBe(3);
+           expect(f.nativeElement.childNodes.length).toBe(2);
          }));
 
       it('should not remove whitespaces when explicitly requested not to do so', async(() => {

packages/platform-browser-dynamic/test/testing_public_browser_spec.ts

@@ -123,7 +123,7 @@ class BadTemplateUrl {
            TestBed.compileComponents().then(() => {
              const componentFixture = TestBed.createComponent(ExternalTemplateComp);
              componentFixture.detectChanges();
-             expect(componentFixture.nativeElement.textContent).toEqual('from external template\n');
+             expect(componentFixture.nativeElement.textContent).toEqual('from external template');
            });
          }),
          10000);  // Long timeout here because this test makes an actual ResourceLoader request, and

packages/platform-browser/test/testing_public_spec.ts

@@ -307,7 +307,7 @@ class CompWithUrlTemplate {
         it('should allow to createSync components with templateUrl after explicit async compilation',
            () => {
              const fixture = TestBed.createComponent(CompWithUrlTemplate);
-             expect(fixture.nativeElement).toHaveText('from external template\n');
+             expect(fixture.nativeElement).toHaveText('from external template');
            });
       });