Add sourcemapBaseUrl option

cli/help.md

@@ -54,6 +54,7 @@ Basic options:
 --no-sanitizeFileName       Do not replace invalid characters in file names
 --shimMissingExports        Create shim variables for missing exports
 --silent                    Don't print warnings
+--sourcemapBaseUrl          Emit absolute sourcemap URLs with base URL prefix, e.g. https://example.com/
 --sourcemapExcludeSources   Do not include source code in source maps
 --sourcemapFile <file>      Specify bundle position for source maps
 --stdin=ext                 Specify file extension used for stdin input

docs/01-command-line-reference.md

@@ -90,6 +90,7 @@ export default {
     preserveModules,
     preserveModulesRoot,
     sourcemap,
+    sourcemapBaseUrl,
     sourcemapExcludeSources,
     sourcemapFile,
     sourcemapPathTransform,
@@ -360,6 +361,7 @@ Many options have command line equivalents. In those cases, any arguments passed
 --no-sanitizeFileName       Do not replace invalid characters in file names
 --shimMissingExports        Create shim variables for missing exports
 --silent                    Don't print warnings
+--sourcemapBaseUrl          Emit absolute sourcemap URLs with base URL prefix, e.g. https://example.com/
 --sourcemapExcludeSources   Do not include source code in source maps
 --sourcemapFile <file>      Specify bundle position for source maps
 --stdin=ext                 Specify file extension used for stdin input

src/rollup/rollup.ts

@@ -284,7 +284,11 @@ async function writeOutputFile(
 			if (outputOptions.sourcemap === 'inline') {
 				url = outputFile.map.toUrl();
 			} else {
-				url = `${basename(outputFile.fileName)}.map`;
+				const { sourcemapBaseUrl } = outputOptions;
+				const sourcemapFileName = `${basename(outputFile.fileName)}.map`;
+				url = sourcemapBaseUrl
+					? new URL(sourcemapFileName, sourcemapBaseUrl).toString()
+					: sourcemapFileName;
 				writeSourceMapPromise = fs.writeFile(`${fileName}.map`, outputFile.map.toString());
 			}
 			if (outputOptions.sourcemap !== 'hidden') {

src/rollup/types.d.ts

@@ -692,6 +692,7 @@ export interface OutputOptions {
 	preserveModulesRoot?: string;
 	sanitizeFileName?: boolean | ((fileName: string) => string);
 	sourcemap?: boolean | 'inline' | 'hidden';
+	sourcemapBaseUrl?: string;
 	sourcemapExcludeSources?: boolean;
 	sourcemapFile?: string;
 	sourcemapPathTransform?: SourcemapPathTransformOption;
@@ -739,6 +740,7 @@ export interface NormalizedOutputOptions {
 	preserveModulesRoot: string | undefined;
 	sanitizeFileName: (fileName: string) => string;
 	sourcemap: boolean | 'inline' | 'hidden';
+	sourcemapBaseUrl: string | undefined;
 	sourcemapExcludeSources: boolean;
 	sourcemapFile: string | undefined;
 	sourcemapPathTransform: SourcemapPathTransformOption | undefined;

src/utils/options/mergeOptions.ts

@@ -263,6 +263,7 @@ function mergeOutputOptions(
 		preserveModulesRoot: getOption('preserveModulesRoot'),
 		sanitizeFileName: getOption('sanitizeFileName'),
 		sourcemap: getOption('sourcemap'),
+		sourcemapBaseUrl: getOption('sourcemapBaseUrl'),
 		sourcemapExcludeSources: getOption('sourcemapExcludeSources'),
 		sourcemapFile: getOption('sourcemapFile'),
 		sourcemapPathTransform: getOption('sourcemapPathTransform'),

src/utils/options/normalizeOutputOptions.ts

@@ -7,9 +7,16 @@ import type {
 	SourcemapPathTransformOption
 } from '../../rollup/types';
 import { ensureArray } from '../ensureArray';
-import { errInvalidExportOptionValue, errInvalidOption, error, warnDeprecation } from '../error';
+import {
+	errFailedValidation,
+	errInvalidExportOptionValue,
+	errInvalidOption,
+	error,
+	warnDeprecation
+} from '../error';
 import { resolve } from '../path';
 import { sanitizeFileName as defaultSanitizeFileName } from '../sanitizeFileName';
+import { isValidUrl } from '../url';
 import {
 	generatedCodePresets,
 	type GenericConfigObject,
@@ -76,6 +83,7 @@ export function normalizeOutputOptions(
 				? id => id
 				: defaultSanitizeFileName,
 		sourcemap: config.sourcemap || false,
+		sourcemapBaseUrl: config.sourcemapBaseUrl ? ensureValidUrl(config.sourcemapBaseUrl) : undefined,
 		sourcemapExcludeSources: config.sourcemapExcludeSources || false,
 		sourcemapFile: config.sourcemapFile,
 		sourcemapPathTransform: config.sourcemapPathTransform as
@@ -471,3 +479,10 @@ const getNamespaceToStringTag = (
 	}
 	return generatedCode.symbols || false;
 };
+
+const ensureValidUrl = (url: string): NormalizedOutputOptions['sourcemapBaseUrl'] => {
+	if (isValidUrl(url)) {
+		return url;
+	}
+	return error(errFailedValidation('Not a valid URL'));
+};

src/utils/url.ts

@@ -0,0 +1,8 @@
+export function isValidUrl(url: string): boolean {
+	try {
+		new URL(url);
+	} catch (_) {
+		return false;
+	}
+	return true;
+}

test/sourcemaps/samples/sourcemap-base-url/_config.js

@@ -0,0 +1,22 @@
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+
+module.exports = {
+	description: 'adds a sourcemap base url',
+	options: {
+		output: {
+			sourcemapBaseUrl: 'https://example.com'
+		}
+	},
+	test: (code, map, profile) => {
+		assert.equal(map.file, `bundle.${profile.format}.js`);
+		const bundlePath = path.join(__dirname, `_actual/bundle.${profile.format}.js`);
+		const bundledCode = fs.readFileSync(bundlePath, { encoding: 'utf8', flag: 'r' });
+		const sourceMappingURL = bundledCode.split('\n').slice(-2)[0];
+		assert.equal(
+			sourceMappingURL,
+			`//# sourceMappingURL=https://example.com/bundle.${profile.format}.js.map`
+		);
+	}
+};

test/sourcemaps/samples/sourcemap-base-url/main.js

@@ -0,0 +1 @@
+console.log( 42 );