Build: Switch from UglifyJS to SWC minify, make the minified file ES5

More recent UglifyJS versions have started converting regular functions to arrow
ones, making ES5 source file migrated to a ES2015+ minified one. We want to
avoid that even in 1.14.x as long as we keep the source file in ES5. But the
bigger problem is that we generate ES2015+ minified code even for 1.13.3
releases which support IE.

Closes jquerygh-629
Ref mishoo/UglifyJS#5967
Ref jquery#629

Author: mgol

Diff for: Gruntfile.js

@@ -11,7 +11,6 @@ grunt.loadNpmTasks( "grunt-check-modules" );
 grunt.loadNpmTasks( "grunt-contrib-clean" );
 grunt.loadNpmTasks( "grunt-contrib-copy" );
 grunt.loadNpmTasks( "grunt-contrib-handlebars" );
-grunt.loadNpmTasks( "grunt-contrib-uglify" );
 grunt.loadNpmTasks( "grunt-eslint" );
 
 grunt.initConfig( {
@@ -61,10 +60,7 @@ grunt.initConfig( {
 			dest: "app/dist"
 		}
 	},
-	uglify: {
-		options: {
-			preserveComments: "some"
-		},
+	minify: {
 
 		// DownloadBuilder minified frontend bundle
 		download: {
@@ -87,6 +83,9 @@ grunt.initConfig( {
 	}
 } );
 
+// local tasks
+grunt.loadTasks( "grunt-tasks" );
+
 function log( callback, successMsg, errorMsg ) {
 	return function( error, result, code ) {
 		if ( error && errorMsg ) {
@@ -279,7 +278,7 @@ function buildPackages( folder, callback ) {
 
 grunt.registerTask( "default", [ "check-modules", "eslint", "test" ] );
 
-grunt.registerTask( "build-app", [ "clean", "handlebars", "copy", "uglify" ] );
+grunt.registerTask( "build-app", [ "clean", "handlebars", "copy", "minify" ] );
 
 grunt.registerTask( "build-packages", "Builds zip package of each jQuery UI release specified in config file with all components and lightness theme, inside the given folder", function( folder ) {
 	var done = this.async();

Diff for: grunt-tasks/minify.js

@@ -0,0 +1,26 @@
+"use strict";
+
+const swc = require( "@swc/core" );
+const swcOptions = require( "../lib/swc-options" );
+
+module.exports = function( grunt ) {
+
+grunt.registerMultiTask( "minify", async function() {
+	const done = this.async();
+
+	for ( const file of this.files ) {
+		const contents = file.src
+			.map( singleFile => grunt.file.read( singleFile ) )
+			.join( "\n" );
+
+		const { code } = await swc.minify( contents, swcOptions );
+
+		grunt.file.write( file.dest, code );
+
+		grunt.log.writeln( `File ${ file.dest } created.` );
+	}
+
+	done();
+} );
+
+};

Diff for: lib/jquery-ui-files.js

@@ -5,7 +5,8 @@ var stripBanner, glob, noDirectory,
 	fs = require( "node:fs" ),
 	path = require( "node:path" ),
 	sqwish = require( "sqwish" ),
-	UglifyJS = require( "uglify-js" ),
+	swc = require( "@swc/core" ),
+	swcOptions = require( "./swc-options" ),
 	util = require( "./util" ),
 	Files = require( "./files" ),
 	filesCache = {};
@@ -91,7 +92,10 @@ JqueryUiFiles.prototype = {
 				path: file.path.replace( /\.([^.]*)$/, ".min.$1" )
 			};
 			if ( ( /\.js$/i ).test( file.path ) ) {
-				minified[ file.path ].data = UglifyJS.minify( file.data.toString( "utf8" ) ).code;
+				minified[ file.path ].data = swc.minifySync(
+					file.data.toString( "utf8" ),
+					swcOptions
+				).code;
 			} else if ( ( /\.css$/i ).test( file.path ) ) {
 				minified[ file.path ].data = sqwish.minify( file.data.toString( "utf8" ) );
 			}

Diff for: lib/package.js

@@ -11,7 +11,8 @@ var indexTemplate,
 	sqwish = require( "sqwish" ),
 	ThemeRoller = require( "./themeroller" ),
 	semver = require( "semver" ),
-	UglifyJS = require( "uglify-js" );
+	swc = require( "@swc/core" ),
+	swcOptions = require( "./swc-options" );
 
 indexTemplate = handlebars.compile( fs.readFileSync( __dirname + "/../template/zip/index.html", "utf8" ) );
 
@@ -340,13 +341,8 @@ extend( Package.prototype, {
 		}
 
 		this.jsBundle.promise.then( function( js ) {
-			var minJs;
 			var _banner = banner( pkgJson, jsFileNames, { minify: true } );
-			var uglifyResult = UglifyJS.minify( js );
-			if ( uglifyResult.error ) {
-				throw uglifyResult.error;
-			}
-			minJs = uglifyResult.code;
+			var minJs = swc.minifySync( js, swcOptions ).code;
 			callback( null, _banner + minJs );
 		} ).catch( callback );
 	},

Diff for: lib/swc-options.js

@@ -0,0 +1,21 @@
+"use strict";
+
+module.exports = {
+	compress: {
+		ecma: 5,
+		hoist_funs: false,
+		loops: false
+	},
+	format: {
+		ecma: 5,
+		asciiOnly: true,
+
+		// That only preserves license comments.
+		// See https://swc.rs/docs/configuration/minification#note-about-comments
+		comments: true
+	},
+	inlineSourcesContent: false,
+	mangle: true,
+	module: false,
+	sourceMap: false
+};