From 27303c6be09b8fc24c13454deae234e480cbf995 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Go=C5=82=C4=99biowski-Owczarek?=
 <m.goleb@gmail.com>
Date: Wed, 31 May 2023 18:59:35 +0200
Subject: [PATCH] Build: Switch the minifier from UglifyJS to Terser

UglifyJS is ES5-only, while Terser supports newer ECMAScript versions. jQuery
is authored in ES5 but jQuery 4.x will also have an ESM build that cannot be
minified using UglifyJS directly.

We could strip the `export` statement, minify via UglifyJS and re-add one but
that increases complexity & may not fully play nice with source maps.

On the other hand, switching to Terser increases the minfied size by just 324
bytes and the minified gzipped one by just 70 bytes. Such differences largely
disappear among bigger size gains from the `3.x-stable` line - around 2.7 KB
minified gzipped as of now.

Closes gh-5258
---
 Gruntfile.js             | 27 ++++++++++++++-------------
 build/tasks/build.js     |  2 +-
 build/tasks/sourcemap.js |  2 +-
 package.json             |  6 +++---
 4 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/Gruntfile.js b/Gruntfile.js
index c5e238ced..9029be85d 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -333,25 +333,26 @@ module.exports = function( grunt ) {
 			files: [ "<%= eslint.dev.src %>" ],
 			tasks: [ "dev" ]
 		},
-		uglify: {
+		terser: {
 			all: {
 				files: {
 					"dist/<%= grunt.option('filename').replace('.js', '.min.js') %>":
 						"dist/<%= grunt.option('filename') %>"
 				},
 				options: {
-					preserveComments: false,
-					sourceMap: true,
-					sourceMapName:
-						"dist/<%= grunt.option('filename').replace('.js', '.min.map') %>",
-					report: "min",
-					output: {
-						"ascii_only": true
+					ecma: 5,
+					sourceMap: {
+						filename: "dist/<%= grunt.option('filename').replace('.js', '.min.map') %>"
+					},
+					format: {
+						ascii_only: true,
+						comments: false,
+						preamble: "/*! jQuery v<%= pkg.version %> | " +
+							"(c) OpenJS Foundation and other contributors | " +
+							"jquery.org/license */"
 					},
-					banner: "/*! jQuery v<%= pkg.version %> | " +
-						"(c) OpenJS Foundation and other contributors | jquery.org/license */",
 					compress: {
-						"hoist_funs": false,
+						hoist_funs: false,
 						loops: false
 					}
 				}
@@ -420,7 +421,7 @@ module.exports = function( grunt ) {
 	grunt.registerTask( "dev", [
 		"build:*:*",
 		runIfNewNode( "newer:eslint:dev" ),
-		"newer:uglify",
+		"newer:terser",
 		"remove_map_comment",
 		"dist:*",
 		"qunit_fixture",
@@ -431,7 +432,7 @@ module.exports = function( grunt ) {
 		runIfNewNode( "eslint:dev" ),
 		"build:*:*",
 		"amd",
-		"uglify",
+		"terser",
 		"remove_map_comment",
 		"dist:*",
 		"test:prepare",
diff --git a/build/tasks/build.js b/build/tasks/build.js
index bcfa8ceae..98d95cbe5 100644
--- a/build/tasks/build.js
+++ b/build/tasks/build.js
@@ -339,6 +339,6 @@ module.exports = function( grunt ) {
 			"";
 
 		grunt.log.writeln( "Creating custom build...\n" );
-		grunt.task.run( [ "build:*:*" + ( modules ? ":" + modules : "" ), "uglify", "dist" ] );
+		grunt.task.run( [ "build:*:*" + ( modules ? ":" + modules : "" ), "terser", "dist" ] );
 	} );
 };
diff --git a/build/tasks/sourcemap.js b/build/tasks/sourcemap.js
index 509374f2e..f6ef5698e 100644
--- a/build/tasks/sourcemap.js
+++ b/build/tasks/sourcemap.js
@@ -3,7 +3,7 @@
 var fs = require( "fs" );
 
 module.exports = function( grunt ) {
-	var config = grunt.config( "uglify.all.files" );
+	var config = grunt.config( "terser.all.files" );
 	grunt.registerTask( "remove_map_comment", function() {
 		var minLoc = grunt.config.process( Object.keys( config )[ 0 ] );
 
diff --git a/package.json b/package.json
index 31166d31f..56eaa6822 100644
--- a/package.json
+++ b/package.json
@@ -35,7 +35,6 @@
     "grunt-babel": "8.0.0",
     "grunt-cli": "1.4.3",
     "grunt-compare-size": "0.4.2",
-    "grunt-contrib-uglify": "3.4.0",
     "grunt-contrib-watch": "1.1.0",
     "grunt-eslint": "24.0.0",
     "grunt-git-authors": "3.2.0",
@@ -43,6 +42,7 @@
     "grunt-karma": "4.0.2",
     "grunt-newer": "1.3.0",
     "grunt-npmcopy": "0.2.0",
+    "grunt-terser": "2.0.0",
     "gzip-js": "0.3.2",
     "husky": "4.2.5",
     "jsdom": "19.0.0",
@@ -67,8 +67,8 @@
     "rollup": "2.21.0",
     "sinon": "7.3.1",
     "strip-json-comments": "3.1.1",
-    "testswarm": "1.1.2",
-    "uglify-js": "3.4.7"
+    "terser": "5.17.6",
+    "testswarm": "1.1.2"
   },
   "scripts": {
     "build": "npm install && grunt",