362 lines
9.5 KiB
JavaScript
362 lines
9.5 KiB
JavaScript
import path from 'node:path';
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import coreJsCompat from 'core-js-compat';
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import {camelCase} from 'change-case';
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import isStaticRequire from './ast/is-static-require.js';
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import {readPackageJson} from './shared/package-json.js';
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const {data: compatData, entries: coreJsEntries} = coreJsCompat;
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const MESSAGE_ID_POLYFILL = 'unnecessaryPolyfill';
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const MESSAGE_ID_CORE_JS = 'unnecessaryCoreJsModule';
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const messages = {
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[MESSAGE_ID_POLYFILL]: 'Use built-in instead.',
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[MESSAGE_ID_CORE_JS]:
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'All polyfilled features imported from `{{coreJsModule}}` are available as built-ins. Use the built-ins instead.',
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};
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const additionalPolyfillModules = {
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'es.promise.finally': ['p-finally'],
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'es.object.set-prototype-of': ['setprototypeof'],
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'es.string.code-point-at': ['code-point-at'],
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};
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const additionalPolyfillPatterns = Object.fromEntries(Object.entries(additionalPolyfillModules).map(([feature, modules]) => [feature, `|(${modules.join('|')})`]));
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const prefixes = '(mdn-polyfills/|polyfill-)';
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const suffixes = '(-polyfill)';
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const delimiter = String.raw`(\.|-|\.prototype\.|/)?`;
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const moduleDelimiter = /[./-]/u;
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const getFirstSegment = value => {
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const [firstSegment = ''] = value.split(moduleDelimiter);
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return firstSegment;
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};
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const stripPolyfillPrefix = value => {
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if (value.startsWith('polyfill-')) {
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return value.slice('polyfill-'.length);
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}
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if (value.startsWith('mdn-polyfills/')) {
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return value.slice('mdn-polyfills/'.length);
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}
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return value;
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};
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function addPolyfillToken(tokens, value) {
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if (!value) {
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return;
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}
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const lowercaseValue = value.toLowerCase();
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tokens.add(lowercaseValue);
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tokens.add(getFirstSegment(lowercaseValue));
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const camelCasedValue = camelCase(value).toLowerCase();
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tokens.add(camelCasedValue);
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tokens.add(getFirstSegment(camelCasedValue));
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}
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const polyfills = Object.keys(compatData).map(feature => {
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const [rawEcmaVersion, rawConstructorName, rawMethodName = ''] = feature.split('.');
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let ecmaVersion = rawEcmaVersion;
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let constructorName = rawConstructorName;
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let methodName = rawMethodName;
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if (ecmaVersion === 'es') {
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ecmaVersion = String.raw`(es\d*)`;
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}
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constructorName = `(${constructorName}|${camelCase(constructorName)})`;
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methodName &&= `(${methodName}|${camelCase(methodName)})`;
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const methodOrConstructor = methodName || constructorName;
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const patterns = [
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`^((${prefixes}?(`,
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methodName && `(${ecmaVersion}${delimiter}${constructorName}${delimiter}${methodName})|`, // Ex: es6-array-copy-within
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methodName && `(${constructorName}${delimiter}${methodName})|`, // Ex: array-copy-within
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`(${ecmaVersion}${delimiter}${constructorName}))`, // Ex: es6-array
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`${suffixes}?)|`,
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`(${prefixes}${methodOrConstructor}|${methodOrConstructor}${suffixes})`, // Ex: polyfill-copy-within / polyfill-promise
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`${additionalPolyfillPatterns[feature] || ''})$`,
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];
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return {
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feature,
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pattern: new RegExp(patterns.join(''), 'i'),
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tokens: (() => {
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const tokens = new Set();
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if (rawEcmaVersion === 'es') {
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tokens.add('es');
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} else {
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addPolyfillToken(tokens, rawEcmaVersion);
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}
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addPolyfillToken(tokens, rawConstructorName);
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addPolyfillToken(tokens, rawMethodName);
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for (const module of additionalPolyfillModules[feature] || []) {
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addPolyfillToken(tokens, module);
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}
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return tokens;
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})(),
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};
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});
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const polyfillsByToken = new Map();
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const polyfillTokensByFirstCharacter = new Map();
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const esConstructorTokens = new Set();
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for (const polyfill of polyfills) {
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const [ecmaVersion, constructorName] = polyfill.feature.split('.');
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if (ecmaVersion === 'es') {
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esConstructorTokens.add(constructorName.toLowerCase());
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esConstructorTokens.add(camelCase(constructorName).toLowerCase());
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}
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for (const token of polyfill.tokens) {
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if (!token) {
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continue;
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}
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if (polyfillsByToken.has(token)) {
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polyfillsByToken.get(token).push(polyfill);
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} else {
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polyfillsByToken.set(token, [polyfill]);
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}
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const firstCharacter = token[0];
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if (polyfillTokensByFirstCharacter.has(firstCharacter)) {
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polyfillTokensByFirstCharacter.get(firstCharacter).add(token);
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} else {
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polyfillTokensByFirstCharacter.set(firstCharacter, new Set([token]));
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}
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}
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}
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const hasEsConstructorPrefix = value => {
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for (const token of esConstructorTokens) {
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if (value.startsWith(token)) {
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return true;
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}
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}
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return false;
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};
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const isPotentialEsPrefix = importedModule => {
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if (!importedModule.startsWith('es')) {
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return false;
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}
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let constructorIndex = 2;
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while (
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constructorIndex < importedModule.length
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&& importedModule[constructorIndex] >= '0'
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&& importedModule[constructorIndex] <= '9'
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) {
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constructorIndex++;
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}
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if (importedModule.startsWith('.prototype.', constructorIndex)) {
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constructorIndex += '.prototype.'.length;
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} else if (['.', '-', '/'].includes(importedModule[constructorIndex])) {
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constructorIndex++;
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}
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return hasEsConstructorPrefix(importedModule.slice(constructorIndex));
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};
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const getPolyfillCandidates = importedModule => {
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const normalizedImportedModule = stripPolyfillPrefix(importedModule);
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if (!normalizedImportedModule) {
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return;
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}
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const firstCharacter = normalizedImportedModule[0];
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const tokens = polyfillTokensByFirstCharacter.get(firstCharacter);
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if (!tokens) {
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return;
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}
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const candidates = new Set();
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const firstSegment = getFirstSegment(normalizedImportedModule);
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if (firstSegment === normalizedImportedModule) {
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for (const token of tokens) {
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if (token === 'es') {
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if (!isPotentialEsPrefix(normalizedImportedModule)) {
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continue;
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}
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} else if (!normalizedImportedModule.startsWith(token)) {
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continue;
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}
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for (const polyfill of polyfillsByToken.get(token)) {
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candidates.add(polyfill);
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}
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}
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} else {
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for (const token of tokens) {
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if (
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token === 'es'
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|| !firstSegment.startsWith(token)
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) {
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continue;
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}
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for (const polyfill of polyfillsByToken.get(token)) {
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candidates.add(polyfill);
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}
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}
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}
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if (isPotentialEsPrefix(normalizedImportedModule)) {
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for (const polyfill of polyfillsByToken.get('es') || []) {
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candidates.add(polyfill);
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}
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}
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if (candidates.size === 0) {
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return;
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}
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return [...candidates];
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};
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function getTargets(options, dirname) {
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if (options?.targets) {
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return options.targets;
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}
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const packageJsonResult = readPackageJson(dirname);
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if (!packageJsonResult) {
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return;
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}
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const {browserslist, engines} = packageJsonResult.packageJson;
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return browserslist ?? engines;
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}
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function create(context) {
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const targets = getTargets(context.options[0], path.dirname(context.filename));
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if (!targets) {
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return;
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}
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let unavailableFeatures;
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try {
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unavailableFeatures = coreJsCompat({targets}).list;
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} catch {
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// This can happen if the targets are invalid or use unsupported syntax like `{node:'*'}`.
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return;
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}
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const unavailableFeatureSet = new Set(unavailableFeatures);
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// When core-js graduates a feature from `esnext` to `es`, the entries list both (e.g. `['es.regexp.escape', 'esnext.regexp.escape']`),
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// but `coreJsCompat` only includes the `es` version in its unavailable list, making the `esnext` version appear "available".
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// To avoid false positives, treat `esnext.*` features as unavailable when their `es.*` counterpart is already in the list.
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const checkFeatures = features => !features.every(feature =>
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unavailableFeatureSet.has(feature)
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|| (feature.startsWith('esnext.') && features.includes(feature.replace('esnext.', 'es.'))));
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context.on('Literal', node => {
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if (
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!(
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(['ImportDeclaration', 'ImportExpression'].includes(node.parent.type) && node.parent.source === node)
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|| (isStaticRequire(node.parent) && node.parent.arguments[0] === node)
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)
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) {
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return;
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}
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const importedModule = node.value;
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if (typeof importedModule !== 'string' || ['.', '/'].includes(importedModule[0])) {
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return;
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}
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const coreJsModuleFeatures = coreJsEntries[importedModule.replace('core-js-pure', 'core-js')];
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if (coreJsModuleFeatures) {
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if (coreJsModuleFeatures.length > 1) {
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if (checkFeatures(coreJsModuleFeatures)) {
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return {
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node,
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messageId: MESSAGE_ID_CORE_JS,
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data: {
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coreJsModule: importedModule,
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},
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};
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}
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} else if (!unavailableFeatureSet.has(coreJsModuleFeatures[0])) {
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return {node, messageId: MESSAGE_ID_POLYFILL};
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}
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return;
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}
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const polyfillCandidates = getPolyfillCandidates(importedModule.toLowerCase());
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if (!polyfillCandidates) {
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return;
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}
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const polyfill = polyfillCandidates.find(({pattern}) => pattern.test(importedModule));
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if (polyfill) {
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const [, namespace, method = ''] = polyfill.feature.split('.');
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const features = coreJsEntries[`core-js/full/${namespace}${method && '/'}${method}`];
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if (features && checkFeatures(features)) {
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return {node, messageId: MESSAGE_ID_POLYFILL};
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}
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}
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});
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}
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const schema = [
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{
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type: 'object',
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additionalProperties: false,
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required: ['targets'],
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properties: {
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targets: {
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oneOf: [
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{
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type: 'string',
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description: 'A browserslist query string.',
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},
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{
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type: 'array',
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description: 'An array of browserslist query strings.',
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},
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{
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type: 'object',
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description: 'A browserslist targets object.',
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},
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],
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description: 'The target environments.',
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},
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},
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},
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];
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/** @type {import('eslint').Rule.RuleModule} */
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const config = {
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create,
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meta: {
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type: 'suggestion',
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docs: {
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description: 'Enforce the use of built-in methods instead of unnecessary polyfills.',
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recommended: 'unopinionated',
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},
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schema,
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// eslint-disable-next-line eslint-plugin/require-meta-default-options
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defaultOptions: [],
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messages,
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},
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};
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export default config;
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