have the js API write to stdout by default

cmd/esbuild/service.go

@@ -356,15 +356,9 @@ func (service *serviceType) handleBuildRequest(id uint32, request map[string]int
 	// Normally when "write" is true and there is no output file/directory then
 	// the output is written to stdout instead. However, we're currently using
 	// stdout as a communication channel and writing the build output to stdout
-	// would corrupt our protocol.
-	//
-	// While we could channel this back to the host process and write it to
-	// stdout there, the public Go API we're about to call doesn't have an option
-	// for "write to stdout but don't actually write" and I don't think it should.
-	// For now let's just forbid this case because it's not even that useful.
-	if err == nil && !isServe && write && options.Outfile == "" && options.Outdir == "" {
-		err = errors.New("Either provide \"outfile\" or set \"write\" to false")
-	}
+	// would corrupt our protocol. Special-case this to channel this back to the
+	// host process and write it to stdout there.
+	writeToStdout := err == nil && !isServe && write && options.Outfile == "" && options.Outdir == ""
 
 	if err != nil {
 		return outgoingPacket{bytes: encodeErrorPacket(id, err)}
@@ -420,6 +414,9 @@ func (service *serviceType) handleBuildRequest(id uint32, request map[string]int
 		if options.Metafile {
 			response["metafile"] = result.Metafile
 		}
+		if writeToStdout && len(result.OutputFiles) == 1 {
+			response["writeToStdout"] = result.OutputFiles[0].Contents
+		}
 		return response
 	}
 
@@ -433,7 +430,9 @@ func (service *serviceType) handleBuildRequest(id uint32, request map[string]int
 		}
 	}
 
-	options.Write = write
+	if !writeToStdout {
+		options.Write = write
+	}
 	options.Incremental = incremental
 	result := api.Build(options)
 	response := resultToResponse(result)

lib/common.ts

@@ -848,6 +848,7 @@ export function createChannel(streamIn: StreamIn): StreamOut {
             let result: types.BuildResult = { warnings };
             if (response!.outputFiles) result.outputFiles = response!.outputFiles.map(convertOutputFiles);
             if (response!.metafile) result.metafile = JSON.parse(response!.metafile);
+            if (response!.writeToStdout !== void 0) console.log(protocol.decodeUTF8(response!.writeToStdout).replace(/\n$/, ''));
 
             // Handle incremental rebuilds
             if (response!.rebuildID !== void 0) {

lib/stdio_protocol.ts

@@ -49,6 +49,7 @@ export interface BuildResponse {
   warnings: types.Message[];
   outputFiles: BuildOutputFile[];
   metafile: string;
+  writeToStdout?: Uint8Array;
   rebuildID?: number;
   watchID?: number;
 }