| /** |
| * @fileoverview Disallow shadowing of NaN, undefined, and Infinity (ES5 section 15.1.1) |
| * @author Michael Ficarra |
| */ |
| "use strict"; |
| |
| /** |
| * Determines if a variable safely shadows undefined. |
| * This is the case when a variable named `undefined` is never assigned to a value (i.e. it always shares the same value |
| * as the global). |
| * @param {eslintScope.Variable} variable The variable to check |
| * @returns {boolean} true if this variable safely shadows `undefined` |
| */ |
| function safelyShadowsUndefined(variable) { |
| return variable.name === "undefined" && |
| variable.references.every(ref => !ref.isWrite()) && |
| variable.defs.every(def => def.node.type === "VariableDeclarator" && def.node.init === null); |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Rule Definition |
| //------------------------------------------------------------------------------ |
| |
| module.exports = { |
| meta: { |
| type: "suggestion", |
| |
| docs: { |
| description: "disallow identifiers from shadowing restricted names", |
| category: "Variables", |
| recommended: true, |
| url: "https://eslint.org/docs/rules/no-shadow-restricted-names" |
| }, |
| |
| schema: [] |
| }, |
| |
| create(context) { |
| |
| |
| const RESTRICTED = new Set(["undefined", "NaN", "Infinity", "arguments", "eval"]); |
| |
| return { |
| "VariableDeclaration, :function, CatchClause"(node) { |
| for (const variable of context.getDeclaredVariables(node)) { |
| if (variable.defs.length > 0 && RESTRICTED.has(variable.name) && !safelyShadowsUndefined(variable)) { |
| context.report({ |
| node: variable.defs[0].name, |
| message: "Shadowing of global property '{{idName}}'.", |
| data: { |
| idName: variable.name |
| } |
| }); |
| } |
| } |
| } |
| }; |
| |
| } |
| }; |