fix #650: add "--sourcemap=both"

CHANGELOG.md

@@ -14,6 +14,10 @@
 
     In that case, transforming the code by inverting the condition and moving the following statements inside the branch is not valid because the function is no longer hoisted to above the branch condition. This release fixes the regression by avoiding this optimization in cases like this.
 
+* Add the option `--sourcemap=both` ([#650](https://github.com/evanw/esbuild/issues/650))
+
+    This new option puts the generated source map both an inline `//# sourceMappingURL=` data URL comment inside the output file and in an external file next to the output file. Using it is also possible with the transform API, which will cause it to return both an inline data URL comment in the `code` value and the source map JSON in the `map` value.
+
 * Tree-shake unused code with `--format=iife` ([#639](https://github.com/evanw/esbuild/issues/639))
 
     When the output format is IIFE (which wraps the code in an immediately-invoked function expression), esbuild now assumes that it's safe to remove unused code. This is an assumption that esbuild always makes when bundling but that esbuild previously didn't make when not bundling. Now esbuild will remove code even when not bundling as long as the output format is IIFE.

internal/bundler/linker.go

@@ -3820,15 +3820,27 @@ func (repr *chunkReprJS) generate(c *linkerContext, chunk *chunkInfo) func([]ast
 
 		if c.options.SourceMap != config.SourceMapNone {
 			sourceMap := c.generateSourceMapForChunk(compileResultsForSourceMap, chunkAbsDir, dataForSourceMaps)
-
-			// Store the generated source map
+			var writeDataURL bool
+			var writeFile bool
 			switch c.options.SourceMap {
 			case config.SourceMapInline:
+				writeDataURL = true
+			case config.SourceMapLinkedWithComment, config.SourceMapExternalWithoutComment:
+				writeFile = true
+			case config.SourceMapInlineAndExternal:
+				writeDataURL = true
+				writeFile = true
+			}
+
+			// Write the generated source map as an inline comment
+			if writeDataURL {
 				j.AddString("//# sourceMappingURL=data:application/json;base64,")
 				j.AddString(base64.StdEncoding.EncodeToString(sourceMap))
 				j.AddString("\n")
+			}
 
-			case config.SourceMapLinkedWithComment, config.SourceMapExternalWithoutComment:
+			// Write the generated source map as an external file
+			if writeFile {
 				// Optionally add metadata about the file
 				var jsonMetadataChunk []byte
 				if c.options.AbsMetadataFile != "" {

internal/config/config.go

@@ -47,6 +47,7 @@ const (
 	SourceMapInline
 	SourceMapLinkedWithComment
 	SourceMapExternalWithoutComment
+	SourceMapInlineAndExternal
 )
 
 type Loader int

lib/types.ts

@@ -6,7 +6,7 @@ export type Charset = 'ascii' | 'utf8';
 export type TreeShaking = true | 'ignore-annotations';
 
 interface CommonOptions {
-  sourcemap?: boolean | 'inline' | 'external';
+  sourcemap?: boolean | 'inline' | 'external' | 'both';
   sourcesContent?: boolean;
 
   format?: Format;

pkg/api/api.go

@@ -84,6 +84,7 @@ const (
 	SourceMapInline
 	SourceMapLinked
 	SourceMapExternal
+	SourceMapInlineAndExternal
 )
 
 type SourcesContent uint8

pkg/api/api_impl.go

@@ -65,6 +65,8 @@ func validateSourceMap(value SourceMap) config.SourceMap {
 		return config.SourceMapInline
 	case SourceMapExternal:
 		return config.SourceMapExternalWithoutComment
+	case SourceMapInlineAndExternal:
+		return config.SourceMapInlineAndExternal
 	default:
 		panic("Invalid source map")
 	}

pkg/cli/cli_impl.go

@@ -127,19 +127,23 @@ func parseOptionsImpl(osArgs []string, buildOpts *api.BuildOptions, transformOpt
 			}
 			hasBareSourceMapFlag = true
 
-		case arg == "--sourcemap=external":
-			if buildOpts != nil {
-				buildOpts.Sourcemap = api.SourceMapExternal
-			} else {
-				transformOpts.Sourcemap = api.SourceMapExternal
+		case strings.HasPrefix(arg, "--sourcemap="):
+			value := arg[len("--sourcemap="):]
+			var sourcemap api.SourceMap
+			switch value {
+			case "inline":
+				sourcemap = api.SourceMapInline
+			case "external":
+				sourcemap = api.SourceMapExternal
+			case "both":
+				sourcemap = api.SourceMapInlineAndExternal
+			default:
+				return fmt.Errorf("Invalid sourcemap: %q (valid: inline, external, both)", value)
 			}
-			hasBareSourceMapFlag = false
-
-		case arg == "--sourcemap=inline":
 			if buildOpts != nil {
-				buildOpts.Sourcemap = api.SourceMapInline
+				buildOpts.Sourcemap = sourcemap
 			} else {
-				transformOpts.Sourcemap = api.SourceMapInline
+				transformOpts.Sourcemap = sourcemap
 			}
 			hasBareSourceMapFlag = false
 

scripts/js-api-tests.js

@@ -117,6 +117,24 @@ let buildTests = {
     assert.strictEqual(json.sourcesContent[0], content)
   },
 
+  async sourceMapBoth({ esbuild, testDir }) {
+    const input = path.join(testDir, 'in.js')
+    const output = path.join(testDir, 'out.js')
+    const content = 'exports.foo = 123'
+    await writeFileAsync(input, content)
+    await esbuild.build({ entryPoints: [input], outfile: output, sourcemap: 'both' })
+    const result = require(output)
+    assert.strictEqual(result.foo, 123)
+    const outputFile = await readFileAsync(output, 'utf8')
+    const match = /\/\/# sourceMappingURL=data:application\/json;base64,(.*)/.exec(outputFile)
+    const json = JSON.parse(Buffer.from(match[1], 'base64').toString())
+    assert.strictEqual(json.version, 3)
+    assert.strictEqual(json.sources[0], path.basename(input))
+    assert.strictEqual(json.sourcesContent[0], content)
+    const outputFileMap = await readFileAsync(output + '.map', 'utf8')
+    assert.strictEqual(Buffer.from(match[1], 'base64').toString(), outputFileMap)
+  },
+
   async sourceMapIncludeSourcesContent({ esbuild, testDir }) {
     const input = path.join(testDir, 'in.js')
     const output = path.join(testDir, 'out.js')
@@ -2010,6 +2028,14 @@ let transformTests = {
     await assertSourceMap(Buffer.from(base64.trim(), 'base64').toString(), 'afile.js')
   },
 
+  async sourceMapBothWithName({ service }) {
+    const { code, map } = await service.transform(`let       x`, { sourcemap: 'both', sourcefile: 'afile.js' })
+    assert(code.startsWith(`let x;\n//# sourceMappingURL=`))
+    await assertSourceMap(map, 'afile.js')
+    const base64 = code.slice(code.indexOf('base64,') + 'base64,'.length)
+    await assertSourceMap(Buffer.from(base64.trim(), 'base64').toString(), 'afile.js')
+  },
+
   async numericLiteralPrinting({ service }) {
     async function checkLiteral(text) {
       const { code } = await service.transform(`return ${text}`, { minify: true })