Leverage terser to mangle/compress the generated js messages (#1086)

This patch implements to leverage [terser](https://www.npmjs.com/package/terser) to mangle/compress the generated `.js`  messages when  `--debug` option not added. If debugging the message files, users can run `generate-messages:dev` to check with the original files, including:

1. Removing the prettier dependency.
2. Integrating terser minification with error handling for JavaScript files.
3. Using a conditional debug flag (isDebug) to determine whether to minify the code.
4. Don't remove the blank line in the generated files because it will be handled by `terser` now.

Fix: #1085

Author: minggangw

package.json

@@ -18,15 +18,15 @@
     "rebuild": "npm run clean && node-gyp -j 16 rebuild",
     "rebuild:dev": "npm run clean && node-gyp -j 16 rebuild --debug",
     "generate-messages": "node scripts/generate_messages.js",
-    "generate-messages:dev": "node scripts/generate_messages.js --debug",
+    "generate-messages:dev": "node scripts/generate_messages.js --debug && npx --yes prettier --ignore-path --write generated/**/*.js",
     "generate-tsd-messages": "node scripts/generate_tsd.js",
-    "clean": "node-gyp clean && npx rimraf@6.0.1 ./generated",
+    "clean": "node-gyp clean && npx rimraf ./generated",
     "install": "npm run rebuild",
     "postinstall": "npm run generate-messages",
     "docs": "cd docs && make",
-    "test": "nyc node --expose-gc ./scripts/run_test.js && npx tsd",
+    "test": "nyc node --expose-gc ./scripts/run_test.js && tsd",
     "lint": "eslint && node ./scripts/cpplint.js",
-    "format": "clang-format -i -style=file ./src/*.cpp ./src/*.hpp && prettier --write \"{lib,rosidl_gen,rostsd_gen,rosidl_parser,types,example,test,scripts,benchmark,rostsd_gen}/**/*.{js,md,ts}\" ./*.{js,md,ts}",
+    "format": "clang-format -i -style=file ./src/*.cpp ./src/*.hpp && npx --yes prettier --write \"{lib,rosidl_gen,rostsd_gen,rosidl_parser,types,example,test,scripts,benchmark,rostsd_gen}/**/*.{js,md,ts}\" ./*.{js,md,ts}",
     "prepare": "husky",
     "coverage": "cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js"
   },
@@ -62,6 +62,7 @@
     "lint-staged": "^15.2.10",
     "mocha": "^11.0.2",
     "nyc": "^17.1.0",
+    "rimraf": "^6.0.1",
     "sinon": "^19.0.2",
     "tree-kill": "^1.2.2",
     "tsd": "^0.31.2",
@@ -79,7 +80,7 @@
     "is-close": "^1.3.3",
     "json-bigint": "^1.0.0",
     "nan": "^2.22.0",
-    "prettier": "^3.4.2",
+    "terser": "^5.39.0",
     "walk": "^2.3.15"
   },
   "husky": {

rosidl_gen/idl_generator.js

@@ -15,7 +15,7 @@
 'use strict';
 
 const dot = require('dot');
-const prettier = require('prettier');
+const { minify } = require('terser');
 const fse = require('fs-extra');
 const path = require('path');
 const parser = require('../rosidl_parser/rosidl_parser.js');
@@ -29,10 +29,6 @@ const dots = dot.process({
   path: path.join(__dirname, '../rosidl_gen/templates'),
 });
 
-function removeEmptyLines(str) {
-  return str.replace(/^\s*\n/gm, '');
-}
-
 /**
  * Output generated code to disk. Do not overwrite
  * an existing file. If file already exists do nothing.
@@ -41,11 +37,18 @@ function removeEmptyLines(str) {
  * @param {string} code
  */
 async function writeGeneratedCode(dir, fileName, code) {
-  if (fileName.endsWith('.js')) {
-    code = await prettier.format(code, { parser: 'babel' });
+  let result = null;
+  if (!isDebug && fileName.endsWith('.js')) {
+    try {
+      result = await minify(code);
+    } catch (error) {
+      console.error(`Error minifying ${fileName}:`, error);
+      result = null;
+    }
   }
+
   await fse.mkdirs(dir);
-  await fse.writeFile(path.join(dir, fileName), code);
+  await fse.writeFile(path.join(dir, fileName), result ? result.code : code);
 }
 
 async function generateServiceJSStruct(
@@ -61,9 +64,7 @@ async function generateServiceJSStruct(
     '__' +
     serviceInfo.interfaceName +
     '.js';
-  const generatedSrvCode = removeEmptyLines(
-    dots.service({ serviceInfo: serviceInfo })
-  );
+  const generatedSrvCode = dots.service({ serviceInfo: serviceInfo });
 
   // We are going to only generate the service JavaScript file if it meets one
   // of the followings:
@@ -84,9 +85,7 @@ async function generateServiceJSStruct(
 
 async function generateServiceEventMsg(serviceInfo, dir) {
   const fileName = serviceInfo.interfaceName + '.msg';
-  const generatedEvent = removeEmptyLines(
-    dots.service_event({ serviceInfo: serviceInfo })
-  );
+  const generatedEvent = dots.service_event({ serviceInfo: serviceInfo });
 
   return writeGeneratedCode(dir, fileName, generatedEvent).then(() => {
     serviceInfo.interfaceName += '_Event';
@@ -119,14 +118,12 @@ async function generateServiceEventJSStruct(msgInfo, dir) {
   // const AddTwoInts_RequestWrapper = require('../../generated/example_interfaces/example_interfaces__srv__AddTwoInts_Request.js');
   // const AddTwoInts_ResponseWrapper = require('../../generated/example_interfaces/example_interfaces__srv__AddTwoInts_Response.js');
   msgInfo.isServiceEvent = true;
-  const generatedCode = removeEmptyLines(
-    dots.message({
-      messageInfo: msgInfo,
-      spec: spec,
-      json: JSON.stringify(spec, null, '  '),
-      isDebug: isDebug,
-    })
-  );
+  const generatedCode = dots.message({
+    messageInfo: msgInfo,
+    spec: spec,
+    json: JSON.stringify(spec, null, '  '),
+    isDebug: isDebug,
+  });
 
   return writeGeneratedCode(dir, eventFileName, generatedCode);
 }
@@ -149,14 +146,12 @@ function generateMessageJSStructFromSpec(messageInfo, dir, spec) {
     spec.msgName +
     '.js';
 
-  const generatedCode = removeEmptyLines(
-    dots.message({
-      messageInfo: messageInfo,
-      spec: spec,
-      json: JSON.stringify(spec, null, '  '),
-      isDebug: isDebug,
-    })
-  );
+  const generatedCode = dots.message({
+    messageInfo: messageInfo,
+    spec: spec,
+    json: JSON.stringify(spec, null, '  '),
+    isDebug: isDebug,
+  });
   return writeGeneratedCode(dir, fileName, generatedCode);
 }
 
@@ -291,9 +286,7 @@ async function generateActionJSStruct(actionInfo, dir) {
     '__' +
     actionInfo.interfaceName +
     '.js';
-  const generatedCode = removeEmptyLines(
-    dots.action({ actionInfo: actionInfo })
-  );
+  const generatedCode = dots.action({ actionInfo: actionInfo });
   dir = path.join(dir, actionInfo.pkgName);
   const action = writeGeneratedCode(dir, fileName, generatedCode);