better-regex.mjs

import {createRequire} from 'node:module';
import {getTester} from './utils/test.mjs';

const {test} = getTester(import.meta);
const require = createRequire(import.meta.url);

const MESSAGE_ID = 'better-regex';

const createError = (original, optimized) => [
	{
		messageId: MESSAGE_ID,
		data: {
			original,
			optimized,
		},
	},
];

const disableSortCharacterClassesOptions = [
	{
		sortCharacterClasses: false,
	},
];

const testCase = (original, optimized) => ({
	code: original,
	output: optimized,
	errors: createError(original, optimized),
});

test({
	valid: [
		// Literal regex
		'const foo = /\\d/',
		'const foo = /\\W/i',
		'const foo = /\\w/gi',
		'const foo = /[a-z]/gi',
		'const foo = /\\d*?/gi',

		// Should not crash ESLint (#446 and #448)
		'/\\{\\{verificationUrl\\}\\}/gu',
		'/^test-(?<name>[a-zA-Z-\\d]+)$/u',

		// Should not suggest wrong regex (#447)
		'/(\\s|\\.|@|_|-)/u',
		'/[\\s.@_-]/u',

		// Should not remove repeating patterns too easily (#769)
		'/http:\\/\\/[^/]+\\/pull\\/commits/gi',

		{
			code: '/[GgHhIiå.Z:a-f"0-8%A*ä]/',
			options: disableSortCharacterClassesOptions,
		},

		// `RegExp()` constructor
		'new RegExp(\'\\d\')',
		'new RegExp(\'\\d\', \'ig\')',
		'new RegExp(\'\\d*?\')',
		'new RegExp(\'[a-z]\', \'i\')',
		'new RegExp(/\\d/)',
		'new RegExp(/\\d/gi)',
		'new RegExp(/\\d/, \'ig\')',
		'new RegExp(/\\d*?/)',
		'new RegExp(/[a-z]/, \'i\')',
		// Not `new`
		'RegExp("[0-9]")',
		// Not `RegExp`
		'new Foo("[0-9]")',
		// `callee` is not `Identifier`
		'new foo.RegExp("[0-9]")',
		// `pattern` is not `Literal`
		'new RegExp(foo)',
		// `patter` is not `string`
		'new RegExp(0)',
		// No arguments
		'new RegExp()',

		// #472
		'/[ ;-]/g',

		// #994
		'/\\s?\\s?/', // https://github.com/DmitrySoshnikov/regexp-tree/issues/216#issuecomment-762073297
		'/\\s{0,2}/',
	],
	invalid: [
		// Literal regex
		{
			code: 'const foo = /\\w/ig',
			errors: createError('/\\w/ig', '/\\w/gi'),
			output: 'const foo = /\\w/gi',
		},
		{
			code: 'const foo = /[0-9]/',
			errors: createError('/[0-9]/', '/\\d/'),
			output: 'const foo = /\\d/',
		},
		{
			code: 'const foo = /[0-9]/ig',
			errors: createError('/[0-9]/ig', '/\\d/gi'),
			output: 'const foo = /\\d/gi',
		},
		{
			code: 'const foo = /[^0-9]/',
			errors: createError('/[^0-9]/', '/\\D/'),
			output: 'const foo = /\\D/',
		},
		{
			code: 'const foo = /[A-Za-z0-9_]/',
			errors: createError('/[A-Za-z0-9_]/', '/\\w/'),
			output: 'const foo = /\\w/',
		},
		{
			code: 'const foo = /[A-Za-z\\d_]/',
			errors: createError('/[A-Za-z\\d_]/', '/\\w/'),
			output: 'const foo = /\\w/',
		},
		{
			code: 'const foo = /[a-zA-Z0-9_]/',
			errors: createError('/[a-zA-Z0-9_]/', '/\\w/'),
			output: 'const foo = /\\w/',
		},
		{
			code: 'const foo = /[a-zA-Z\\d_]/',
			errors: createError('/[a-zA-Z\\d_]/', '/\\w/'),
			output: 'const foo = /\\w/',
		},
		{
			code: 'const foo = /[A-Za-z0-9_]+[0-9]?\\.[A-Za-z0-9_]*/',
			errors: createError('/[A-Za-z0-9_]+[0-9]?\\.[A-Za-z0-9_]*/', '/\\w+\\d?\\.\\w*/'),
			output: 'const foo = /\\w+\\d?\\.\\w*/',
		},
		{
			code: 'const foo = /[a-z0-9_]/i',
			errors: createError('/[a-z0-9_]/i', '/\\w/i'),
			output: 'const foo = /\\w/i',
		},
		{
			code: 'const foo = /[a-z\\d_]/i',
			errors: createError('/[a-z\\d_]/i', '/\\w/i'),
			output: 'const foo = /\\w/i',
		},
		{
			code: 'const foo = /[^A-Za-z0-9_]/',
			errors: createError('/[^A-Za-z0-9_]/', '/\\W/'),
			output: 'const foo = /\\W/',
		},
		{
			code: 'const foo = /[^A-Za-z\\d_]/',
			errors: createError('/[^A-Za-z\\d_]/', '/\\W/'),
			output: 'const foo = /\\W/',
		},
		{
			code: 'const foo = /[^a-z0-9_]/i',
			errors: createError('/[^a-z0-9_]/i', '/\\W/i'),
			output: 'const foo = /\\W/i',
		},
		{
			code: 'const foo = /[^a-z\\d_]/i',
			errors: createError('/[^a-z\\d_]/i', '/\\W/i'),
			output: 'const foo = /\\W/i',
		},
		{
			code: 'const foo = /[^a-z\\d_]/ig',
			errors: createError('/[^a-z\\d_]/ig', '/\\W/gi'),
			output: 'const foo = /\\W/gi',
		},
		{
			code: 'const foo = /[^\\d_a-z]/ig',
			errors: createError('/[^\\d_a-z]/ig', '/\\W/gi'),
			output: 'const foo = /\\W/gi',
		},
		{
			code: 'const foo = /[a-z0-9_]/',
			errors: createError('/[a-z0-9_]/', '/[\\d_a-z]/'),
			output: 'const foo = /[\\d_a-z]/',
		},
		{
			code: 'const foo = /^by @([a-zA-Z0-9-]+)/',
			errors: createError('/^by @([a-zA-Z0-9-]+)/', '/^by @([\\dA-Za-z-]+)/'),
			output: 'const foo = /^by @([\\dA-Za-z-]+)/',
		},
		{
			code: '/[GgHhIiå.Z:a-f"0-8%A*ä]/',
			errors: createError('/[GgHhIiå.Z:a-f"0-8%A*ä]/', '/["%*.0-8:AG-IZa-iäå]/'),
			output: '/["%*.0-8:AG-IZa-iäå]/',
		},
		// Should still use shorthand when disabling sort character classes
		{
			code: '/[a0-9b]/',
			options: disableSortCharacterClassesOptions,
			errors: createError('/[a0-9b]/', '/[a\\db]/'),
			output: '/[a\\db]/',
		},

		// `RegExp()` constructor
		{
			code: 'const foo = new RegExp(\'[0-9]\')',
			errors: createError('[0-9]', '\\d'),
			output: 'const foo = new RegExp(\'\\\\d\')',
		},
		{
			code: 'const foo = new RegExp("[0-9]")',
			errors: createError('[0-9]', '\\d'),
			output: 'const foo = new RegExp("\\\\d")',
		},
		{
			code: 'const foo = new RegExp(\'\\\'[0-9]\\\'\')',
			errors: createError('\'[0-9]\'', '\'\\d\''),
			output: 'const foo = new RegExp(\'\\\'\\\\d\\\'\')',
		},
		{
			code: 'const foo = new RegExp("\'[0-9]\'")',
			errors: createError('\'[0-9]\'', '\'\\d\''),
			output: 'const foo = new RegExp("\'\\\\d\'")',
		},
		{
			code: 'const foo = new RegExp(\'[0-9]\', \'ig\')',
			errors: createError('[0-9]', '\\d'),
			output: 'const foo = new RegExp(\'\\\\d\', \'ig\')',
		},
		{
			code: 'const foo = new RegExp(/[0-9]/)',
			errors: createError('/[0-9]/', '/\\d/'),
			output: 'const foo = new RegExp(/\\d/)',
		},
		{
			code: 'const foo = new RegExp(/[0-9]/, \'ig\')',
			errors: createError('/[0-9]/', '/\\d/'),
			output: 'const foo = new RegExp(/\\d/, \'ig\')',
		},
		{
			code: 'const foo = new RegExp(/[0-9]/)',
			errors: createError('/[0-9]/', '/\\d/'),
			output: 'const foo = new RegExp(/\\d/)',
		},
		{
			code: 'const foo = new RegExp(/[0-9]/, \'ig\')',
			errors: createError('/[0-9]/', '/\\d/'),
			output: 'const foo = new RegExp(/\\d/, \'ig\')',
		},
		{
			code: 'const foo = new RegExp(/^[^*]*[*]?$/)',
			errors: createError('/^[^*]*[*]?$/', '/^[^*]*\\*?$/'),
			output: 'const foo = new RegExp(/^[^*]*\\*?$/)',
		},
		// No `flags`
		{
			code: 'const foo = new RegExp(/[0-9]/)',
			errors: createError('/[0-9]/', '/\\d/'),
			output: 'const foo = new RegExp(/\\d/)',
		},
		// `flags` not `Literal`
		{
			code: 'const foo = new RegExp(/[0-9]/, ig)',
			errors: createError('/[0-9]/', '/\\d/'),
			output: 'const foo = new RegExp(/\\d/, ig)',
		},
		// `flags` not `string`
		{
			code: 'const foo = new RegExp(/[0-9]/, 0)',
			errors: createError('/[0-9]/', '/\\d/'),
			output: 'const foo = new RegExp(/\\d/, 0)',
		},
		// `\s` rewrite
		testCase(
			'/[ \\f\\n\\r\\t\\v\\u00a0\\u1680\\u2000-\\u200a\\u2028\\u2029\\u202f\\u205f\\u3000\\ufeff]+/',
			'/\\s+/',
		),
		// #499
		{
			code: '/^[a-z][a-z0-9\\-]{5,29}$/',
			errors: createError('/^[a-z][a-z0-9\\-]{5,29}$/', '/^[a-z][\\da-z\\-]{5,29}$/'),
			output: '/^[a-z][\\da-z\\-]{5,29}$/',
		},
		// #477
		testCase(
			'/[ \\n\\t\\r\\]]/g',
			'/[\\t\\n\\r \\]]/g',
		),
		testCase(
			'/[ \\n\\t\\r\\f"#\'()/;[\\\\\\]{}]/g',
			'/[\\t\\n\\f\\r "#\'()/;[\\\\\\]{}]/g',
		),
		testCase(
			'/[ \\n\\t\\r\\f(){}:;@!\'"\\\\\\][#]|\\/(?=\\*)/g',
			'/[\\t\\n\\f\\r !"#\'():;@[\\\\\\]{}]|\\/(?=\\*)/g',
		),
		// #994
		testCase(
			'/\\s?\\s?\\s?/',
			'/\\s{0,3}/',
		),
		// Actual message
		{
			code: '/[0-9]/',
			output: '/\\d/',
			errors: [
				{
					message: '/[0-9]/ can be optimized to /\\d/.',
				},
			],
		},

		{
			code: '/(/',
			errors: [
				{
					message: 'Problem parsing /(/: \n\n/(/\n  ^\nUnexpected token: "/" at 1:2.',
				},
			],
			parser: require.resolve('@typescript-eslint/parser'),
		},

		// Not fixable
		{
			code: 'const foo = /[0-9]/.toString',
			errors: createError('/[0-9]/', '/\\d/'),
		},
		{
			code: 'const foo = /[0-9]/.source',
			errors: createError('/[0-9]/', '/\\d/'),
		},
	],
});