refactor: avoid loading babel-loader when running esbuild

This commit refactor the code to avoid loading babel-loader when not needed.

Author: alan-agius4

packages/angular_devkit/build_angular/src/tools/babel/presets/application.ts

@@ -17,6 +17,12 @@ import { strict as assert } from 'assert';
 import browserslist from 'browserslist';
 import * as fs from 'fs';
 import * as path from 'path';
+import { loadEsmModule } from '../../../utils/load-esm';
+
+/**
+ * Cached instance of the compiler-cli linker's needsLinking function.
+ */
+let needsLinking: typeof import('@angular/compiler-cli/linker').needsLinking | undefined;
 
 /**
  * List of browsers which are affected by a WebKit bug where class field
@@ -276,3 +282,23 @@ export default function (api: unknown, options: ApplicationPresetOptions) {
 
   return { presets, plugins };
 }
+
+export async function requiresLinking(path: string, source: string): Promise<boolean> {
+  // @angular/core and @angular/compiler will cause false positives
+  // Also, TypeScript files do not require linking
+  if (/[\\/]@angular[\\/](?:compiler|core)|\.tsx?$/.test(path)) {
+    return false;
+  }
+
+  if (!needsLinking) {
+    // Load ESM `@angular/compiler-cli/linker` using the TypeScript dynamic import workaround.
+    // Once TypeScript provides support for keeping the dynamic import this workaround can be
+    // changed to a direct dynamic import.
+    const linkerModule = await loadEsmModule<typeof import('@angular/compiler-cli/linker')>(
+      '@angular/compiler-cli/linker',
+    );
+    needsLinking = linkerModule.needsLinking;
+  }
+
+  return needsLinking(path, source);
+}

packages/angular_devkit/build_angular/src/tools/babel/webpack-loader.ts

@@ -9,7 +9,11 @@
 import { custom } from 'babel-loader';
 import { loadEsmModule } from '../../utils/load-esm';
 import { VERSION } from '../../utils/package-version';
-import { ApplicationPresetOptions, I18nPluginCreators } from './presets/application';
+import {
+  ApplicationPresetOptions,
+  I18nPluginCreators,
+  requiresLinking,
+} from './presets/application';
 
 interface AngularCustomOptions extends Omit<ApplicationPresetOptions, 'instrumentCode'> {
   instrumentCode?: {
@@ -21,11 +25,6 @@ interface AngularCustomOptions extends Omit<ApplicationPresetOptions, 'instrumen
 
 export type AngularBabelLoaderOptions = AngularCustomOptions & Record<string, unknown>;
 
-/**
- * Cached instance of the compiler-cli linker's needsLinking function.
- */
-let needsLinking: typeof import('@angular/compiler-cli/linker').needsLinking | undefined;
-
 /**
  * Cached instance of the compiler-cli linker's Babel plugin factory function.
  */
@@ -38,26 +37,6 @@ let linkerPluginCreator:
  */
 let i18nPluginCreators: I18nPluginCreators | undefined;
 
-export async function requiresLinking(path: string, source: string): Promise<boolean> {
-  // @angular/core and @angular/compiler will cause false positives
-  // Also, TypeScript files do not require linking
-  if (/[\\/]@angular[\\/](?:compiler|core)|\.tsx?$/.test(path)) {
-    return false;
-  }
-
-  if (!needsLinking) {
-    // Load ESM `@angular/compiler-cli/linker` using the TypeScript dynamic import workaround.
-    // Once TypeScript provides support for keeping the dynamic import this workaround can be
-    // changed to a direct dynamic import.
-    const linkerModule = await loadEsmModule<typeof import('@angular/compiler-cli/linker')>(
-      '@angular/compiler-cli/linker',
-    );
-    needsLinking = linkerModule.needsLinking;
-  }
-
-  return needsLinking(path, source);
-}
-
 // eslint-disable-next-line max-lines-per-function
 export default custom<ApplicationPresetOptions>(() => {
   const baseOptions = Object.freeze({

packages/angular_devkit/build_angular/src/tools/esbuild/javascript-transformer-worker.ts

@@ -8,8 +8,7 @@
 
 import { transformAsync } from '@babel/core';
 import { readFile } from 'node:fs/promises';
-import angularApplicationPreset from '../../tools/babel/presets/application';
-import { requiresLinking } from '../../tools/babel/webpack-loader';
+import angularApplicationPreset, { requiresLinking } from '../../tools/babel/presets/application';
 import { loadEsmModule } from '../../utils/load-esm';
 
 interface JavaScriptTransformRequest {