66 lines
2.2 KiB
JavaScript
66 lines
2.2 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 variable.name === "undefined" &&
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variable.references.every(ref => !ref.isWrite()) &&
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variable.defs.every(def => def.node.type === "VariableDeclarator" && def.node.init === null);
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}
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../shared/types').Rule} */
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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(["undefined", "NaN", "Infinity", "arguments", "eval"]);
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const sourceCode = context.sourceCode;
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return {
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"VariableDeclaration, :function, CatchClause"(node) {
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for (const variable of sourceCode.getDeclaredVariables(node)) {
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if (variable.defs.length > 0 && RESTRICTED.has(variable.name) && !safelyShadowsUndefined(variable)) {
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context.report({
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node: variable.defs[0].name,
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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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