eslint/lib/rules/no-restricted-globals.js

   1 /**
   2  * @fileoverview Restrict usage of specified globals.
   3  * @author Benoît Zugmeyer
   4  */
   5 "use strict";
   6
   7 //------------------------------------------------------------------------------
   8 // Rule Definition
   9 //------------------------------------------------------------------------------
  10
  11 /** @type {import('../shared/types').Rule} */
  12 module.exports = {
  13     meta: {
  14         type: "suggestion",
  15
  16         docs: {
  17             description: "Disallow specified global variables",
  18             recommended: false,
  19             url: "https://eslint.org/docs/rules/no-restricted-globals"
  20         },
  21
  22         schema: {
  23             type: "array",
  24             items: {
  25                 oneOf: [
  26                     {
  27                         type: "string"
  28                     },
  29                     {
  30                         type: "object",
  31                         properties: {
  32                             name: { type: "string" },
  33                             message: { type: "string" }
  34                         },
  35                         required: ["name"],
  36                         additionalProperties: false
  37                     }
  38                 ]
  39             },
  40             uniqueItems: true,
  41             minItems: 0
  42         },
  43
  44         messages: {
  45             defaultMessage: "Unexpected use of '{{name}}'.",
  46             // eslint-disable-next-line eslint-plugin/report-message-format -- Custom message might not end in a period
  47             customMessage: "Unexpected use of '{{name}}'. {{customMessage}}"
  48         }
  49     },
  50
  51     create(context) {
  52
  53         // If no globals are restricted, we don't need to do anything
  54         if (context.options.length === 0) {
  55             return {};
  56         }
  57
  58         const restrictedGlobalMessages = context.options.reduce((memo, option) => {
  59             if (typeof option === "string") {
  60                 memo[option] = null;
  61             } else {
  62                 memo[option.name] = option.message;
  63             }
  64
  65             return memo;
  66         }, {});
  67
  68         /**
  69          * Report a variable to be used as a restricted global.
  70          * @param {Reference} reference the variable reference
  71          * @returns {void}
  72          * @private
  73          */
  74         function reportReference(reference) {
  75             const name = reference.identifier.name,
  76                 customMessage = restrictedGlobalMessages[name],
  77                 messageId = customMessage
  78                     ? "customMessage"
  79                     : "defaultMessage";
  80
  81             context.report({
  82                 node: reference.identifier,
  83                 messageId,
  84                 data: {
  85                     name,
  86                     customMessage
  87                 }
  88             });
  89         }
  90
  91         /**
  92          * Check if the given name is a restricted global name.
  93          * @param {string} name name of a variable
  94          * @returns {boolean} whether the variable is a restricted global or not
  95          * @private
  96          */
  97         function isRestricted(name) {
  98             return Object.prototype.hasOwnProperty.call(restrictedGlobalMessages, name);
  99         }
 100
 101         return {
 102             Program() {
 103                 const scope = context.getScope();
 104
 105                 // Report variables declared elsewhere (ex: variables defined as "global" by eslint)
 106                 scope.variables.forEach(variable => {
 107                     if (!variable.defs.length && isRestricted(variable.name)) {
 108                         variable.references.forEach(reportReference);
 109                     }
 110                 });
 111
 112                 // Report variables not declared at all
 113                 scope.through.forEach(reference => {
 114                     if (isRestricted(reference.identifier.name)) {
 115                         reportReference(reference);
 116                     }
 117                 });
 118
 119             }
 120         };
 121     }
 122 };