feat: support external in legalComments (#301)

README.md

@@ -336,7 +336,7 @@ Type: `boolean`
 Minify JS using equivalent but shorter syntax.
 
 #### legalComments
-Type: `'none' | 'inline' | 'eof'`
+Type: `'none' | 'inline' | 'eof' | 'external'`
 
 Default: `'inline'`
 

src/@types/webpack.d.ts

@@ -5,6 +5,13 @@ declare module 'webpack' {
 	namespace compilation {
 		interface Compilation {
 			getAssets(): Asset[];
+
+			// From Webpack 5
+			emitAsset(
+				file: string,
+				source: Source,
+				assetInfo?: AssetInfo,
+			): void;
 		}
 	}
 

src/minify-plugin.ts

@@ -152,6 +152,13 @@ class ESBuildMinifyPlugin {
 				sourcefile: asset.name,
 			});
 
+			if (result.legalComments) {
+				compilation.emitAsset(
+					`${asset.name}.LEGAL.txt`,
+					new RawSource(result.legalComments),
+				);
+			}
+
 			compilation.updateAsset(
 				asset.name,
 				(

tests/specs/plugin.ts

@@ -383,6 +383,31 @@ export default testSuite(({ describe }, webpack: typeof webpack4 | typeof webpac
 					const file = built.fs.readFileSync('/dist/index.js', 'utf8');
 					expect(file).not.toMatch('//! legal comment');
 				});
+
+				test('minify w/ legalComments - external', async () => {
+					const built = await build(
+						fixtures.legalComments,
+						(config) => {
+							configureEsbuildMinifyPlugin(config, {
+								legalComments: 'external',
+							});
+						},
+						webpack,
+					);
+
+					expect(built.stats.hasWarnings()).toBe(false);
+					expect(built.stats.hasErrors()).toBe(false);
+
+					expect(Object.keys(built.stats.compilation.assets)).toStrictEqual([
+						'index.js',
+						'index.js.LEGAL.txt',
+					]);
+					const file = built.fs.readFileSync('/dist/index.js', 'utf8');
+					expect(file).not.toMatch('//! legal comment');
+
+					const extracted = built.fs.readFileSync('/dist/index.js.LEGAL.txt', 'utf8');
+					expect(extracted).toMatch('//! legal comment');
+				});
 			});
 		});
 

tests/utils.ts

@@ -1,8 +1,8 @@
 import type webpack4 from 'webpack';
 import type webpack5 from 'webpack5';
 import MiniCssExtractPlugin from 'mini-css-extract-plugin';
-import { ESBuildMinifyPlugin } from '../dist/index.js';
-import type { MinifyPluginOptions } from '../dist/interfaces.js';
+import { ESBuildMinifyPlugin } from '../src/index.js';
+import type { MinifyPluginOptions } from '../src/interfaces.js';
 
 const esbuildLoaderPath = require.resolve('../src/');