Make sure to write the index file too

pkg/codegen/nodejs/gen.go

@@ -1751,6 +1751,21 @@ func (ns *namespace) intoIOFiles(ctx *ioContext, parent string) ([]*ioFile, erro
 		files = append(files, nestedFiles...)
 	}
 
+	// Lastly, we write the index file for this directory once.
+	// We don't want to generate the file twice, when this function is called
+	// with input=true and again when input=false, so we only generate it
+	// when input=true.
+	// As a special case, we skip the top-level directory /types/, since that
+	// is written elsewhere.
+	if parent != "./types" && ctx.input {
+		var indexPath = path.Join(dirRoot, "index.ts")
+		var file = newIOFile(indexPath)
+		ctx.mod.genHeader(file.writer(), nil, nil, nil)
+		fmt.Fprintf(file.writer(), "export * from \"./%s\";\n", "input.ts")
+		fmt.Fprintf(file.writer(), "export * from \"./%s\";\n", "output.ts")
+		files = append(files, file)
+	}
+
 	return files, nil
 }