[ESLint] Drive lint warnings to zero

`regexp/recommended` was added unintentionally during the ESLint v9 migration
(cbfeb53) and overrode the curated regex ruleset. Remove that spread so the
hand-picked list at the top of eslint.config.mjs is the active policy. Re-add
11 bug-catching rules from `recommended` that don't fight Prism's grammar
idioms. Disable `prefer-const` to match team convention. Add globals for
`src/plugins/**/demo.js`. Apply minor auto-fixes and inline-disable 4
intentional regex patterns.

869 warnings → 0; lint:ci, build, typecheck, tests, and regex-coverage all pass.

Author: DmitrySharabin

eslint.config.mjs

@@ -39,7 +39,7 @@ const config = [
 			'object-shorthand': ['warn', 'always', { avoidQuotes: true }],
 			'one-var': ['warn', 'never'],
 			'prefer-arrow-callback': 'warn',
-			'prefer-const': ['warn', { 'destructuring': 'all' }],
+			'prefer-const': 'off',
 			'prefer-spread': 'warn',
 
 			// JSDoc
@@ -86,6 +86,22 @@ const config = [
 			'regexp/sort-flags': 'warn',
 			'regexp/strict': 'warn',
 
+			// Bug-catching rules ported from `regexp/recommended`. We don't extend the full
+			// recommended set because most of its remaining rules either flag intentional
+			// Prism grammar patterns (multi-line block matchers, `<MOD>` template substitution,
+			// `[^\s\S]` recursion terminators, `[\r\n]` line endings) or are pure style.
+			'regexp/no-empty-group': 'warn',
+			'regexp/no-empty-string-literal': 'warn',
+			'regexp/no-escape-backspace': 'warn',
+			'regexp/no-invalid-regexp': 'warn',
+			'regexp/no-invisible-character': 'warn',
+			'regexp/no-legacy-features': 'warn',
+			'regexp/no-missing-g-flag': 'warn',
+			'regexp/no-non-standard-flag': 'warn',
+			'regexp/no-potentially-useless-backreference': 'warn',
+			'regexp/no-useless-backreference': 'warn',
+			'regexp/no-useless-dollar-replacements': 'warn',
+
 			// I turned this rule off because we use `hasOwnProperty` in a lot of places
 			// TODO: Think about re-enabling this rule
 			'no-prototype-builtins': 'off',
@@ -115,7 +131,6 @@ const config = [
 		},
 		rules: {
 			...eslintCommentsPlugin.configs.recommended.rules,
-			...regexpPlugin.configs.recommended.rules,
 
 			'no-use-before-define': 'off',
 
@@ -150,6 +165,22 @@ const config = [
 			},
 		},
 	},
+	{
+		// Plugin demo pages — load these globals via <script> tags on the demo HTML
+		files: ['src/plugins/**/demo.js'],
+		languageOptions: {
+			globals: {
+				Prism: 'readonly',
+				JSZip: 'readonly',
+				components: 'readonly',
+				saveAs: 'readonly',
+			},
+		},
+		rules: {
+			// Demo scripts expose globals consumed by HTML attributes (e.g. data-adapter="...")
+			'no-unused-vars': 'off',
+		},
+	},
 	{
 		// Test files
 		files: ['tests/**'],

src/languages/docker.js

@@ -15,6 +15,7 @@ export default {
 
 		const string = /"(?:[^"\\\r\n]|\\(?:\r\n|[\s\S]))*"|'(?:[^'\\\r\n]|\\(?:\r\n|[\s\S]))*'/
 			.source;
+		// eslint-disable-next-line regexp/no-dupe-disjunctions -- the (?!["']) lookahead makes the unquoted alternative disjoint from <STR>
 		const option = /--[\w-]+=(?:<STR>|(?!["'])(?:[^\s\\]|\\.)+)/.source.replace(
 			/<STR>/g,
 			() => string

src/languages/markdown.js

@@ -1,5 +1,3 @@
-import { getTextContent } from '../core/classes/token.js';
-import { withoutTokenize } from '../util/language-util.js';
 import markup from './markup.js';
 
 /** @type {import('../types.d.ts').LanguageProto<'markdown'>} */

src/languages/mongodb.js

@@ -288,6 +288,7 @@ export default {
 				},
 				'builtin': {
 					$before: 'constant',
+					// eslint-disable-next-line regexp/sort-alternatives -- builtinFunctions order kept semantic, not alphabetical
 					pattern: RegExp('\\b(?:' + builtinFunctions.join('|') + ')\\b'),
 					alias: 'keyword',
 				},

src/languages/promql.js

@@ -39,6 +39,7 @@ export default {
 			},
 			'vector-match': {
 				// Match the comma-separated label lists inside vector matching:
+				// eslint-disable-next-line regexp/sort-alternatives -- vectorMatching kept in PromQL docs order
 				pattern: new RegExp('((?:' + vectorMatching.join('|') + ')\\s*)\\([^)]*\\)'),
 				lookbehind: true,
 				inside: {
@@ -86,6 +87,7 @@ export default {
 					},
 				},
 			],
+			// eslint-disable-next-line regexp/sort-alternatives -- keywords concatenates semantically-ordered groups
 			'keyword': new RegExp('\\b(?:' + keywords.join('|') + ')\\b', 'i'),
 			'function': /\b[a-z_]\w*(?=\s*\()/i,
 			'number':

src/languages/python.js

@@ -58,7 +58,7 @@ export default {
 			},
 		},
 		'keyword':
-			/\b(?:_(?=\s*:)|and|as|assert|async|await|break|case|class|continue|def|del|elif|else|except|exec|finally|for|from|global|if|import|in|is|lambda|match|nonlocal|not|or|pass|print|raise|return|try|while|with|yield|lazy)\b/,
+			/\b(?:_(?=\s*:)|and|as|assert|async|await|break|case|class|continue|def|del|elif|else|except|exec|finally|for|from|global|if|import|in|is|lambda|lazy|match|nonlocal|not|or|pass|print|raise|return|try|while|with|yield)\b/,
 		'builtin':
 			/\b(?:__import__|abs|all|any|apply|ascii|basestring|bin|bool|buffer|bytearray|bytes|callable|chr|classmethod|cmp|coerce|compile|complex|delattr|dict|dir|divmod|enumerate|eval|execfile|file|filter|float|format|frozenset|getattr|globals|hasattr|hash|help|hex|id|input|int|intern|isinstance|issubclass|iter|len|list|locals|long|map|max|memoryview|min|next|object|oct|open|ord|pow|property|range|raw_input|reduce|reload|repr|reversed|round|set|setattr|slice|sorted|staticmethod|str|sum|super|tuple|type|unichr|unicode|vars|xrange|zip)\b/,
 		'boolean': /\b(?:False|None|True)\b/,

src/plugins/autoloader/demo.js

@@ -44,7 +44,7 @@ document.querySelector('.download-grammars').addEventListener('click', async ({
 			continue;
 		}
 		let basepath =
-			'https://dev.prismjs.com/' + components.languages.meta.path.replace(/\{id}/g, id);
+			'https://dev.prismjs.com/' + components.languages.meta.path.replace(/\{id\}/g, id);
 		let basename = basepath.substring(basepath.lastIndexOf('/') + 1);
 		files.push([basename + '.js', basepath + '.js']);
 		files.push([basename + '.min.js', basepath + '.min.js']);

src/plugins/toolbar/demo.js

@@ -1,6 +1,6 @@
 Prism.plugins.toolbar.registerButton('hello-world', {
 	text: 'Hello World!', // required
-	onClick: function (env) {
+	onClick (env) {
 		// optional
 		alert(`This code snippet is written in ${env.language}.`);
 	},

src/util/async.js

@@ -67,7 +67,6 @@ export async function allSettled (promises) {
 /**
  * @template T
  * @typedef {Promise<T> & {resolve: (value: T) => void, reject: (reason?: any) => void}} DeferredPromise<T>
- *
  */
 
 /**