89 lines
2.5 KiB
JavaScript
89 lines
2.5 KiB
JavaScript
/**
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* @fileoverview Disallow shadowing of NaN, undefined, and Infinity (ES5 section 15.1.1)
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* @author Michael Ficarra
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*/
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'use strict';
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/**
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* Determines if a variable safely shadows undefined.
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* This is the case when a variable named `undefined` is never assigned to a value (i.e. it always shares the same value
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* as the global).
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* @param {eslintScope.Variable} variable The variable to check
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* @returns {boolean} true if this variable safely shadows `undefined`
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*/
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function safelyShadowsUndefined(variable) {
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return (
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variable.name === 'undefined' &&
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variable.references.every((ref) => !ref.isWrite()) &&
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variable.defs.every(
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(def) => def.node.type === 'VariableDeclarator' && def.node.init === null
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)
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);
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}
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../types').Rule.RuleModule} */
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module.exports = {
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meta: {
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type: 'suggestion',
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docs: {
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description: 'Disallow identifiers from shadowing restricted names',
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recommended: true,
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url: 'https://eslint.org/docs/latest/rules/no-shadow-restricted-names',
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},
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schema: [],
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messages: {
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shadowingRestrictedName: "Shadowing of global property '{{name}}'.",
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},
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},
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create(context) {
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const RESTRICTED = new Set([
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'undefined',
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'NaN',
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'Infinity',
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'arguments',
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'eval',
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]);
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const sourceCode = context.sourceCode;
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// Track reported nodes to avoid duplicate reports. For example, on class declarations.
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const reportedNodes = new Set();
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return {
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'VariableDeclaration, :function, CatchClause, ImportDeclaration, ClassDeclaration, ClassExpression'(
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node
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) {
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for (const variable of sourceCode.getDeclaredVariables(node)) {
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if (
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variable.defs.length > 0 &&
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RESTRICTED.has(variable.name) &&
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!safelyShadowsUndefined(variable)
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) {
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for (const def of variable.defs) {
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const nodeToReport = def.name;
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if (!reportedNodes.has(nodeToReport)) {
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reportedNodes.add(nodeToReport);
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context.report({
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node: nodeToReport,
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messageId: 'shadowingRestrictedName',
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data: {
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name: variable.name,
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},
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});
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}
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}
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}
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}
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},
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};
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},
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};
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