eslint/lib/rules/no-native-reassign.js

   1 /**
   2  * @fileoverview Rule to disallow assignments to native objects or read-only global variables
   3  * @author Ilya Volodin
   4  * @deprecated in ESLint v3.3.0
   5  */
   6
   7 "use strict";
   8
   9 //------------------------------------------------------------------------------
  10 // Rule Definition
  11 //------------------------------------------------------------------------------
  12
  13 module.exports = {
  14     meta: {
  15         type: "suggestion",
  16
  17         docs: {
  18             description: "disallow assignments to native objects or read-only global variables",
  19             category: "Best Practices",
  20             recommended: false,
  21             url: "https://eslint.org/docs/rules/no-native-reassign"
  22         },
  23
  24         deprecated: true,
  25
  26         replacedBy: ["no-global-assign"],
  27
  28         schema: [
  29             {
  30                 type: "object",
  31                 properties: {
  32                     exceptions: {
  33                         type: "array",
  34                         items: { type: "string" },
  35                         uniqueItems: true
  36                     }
  37                 },
  38                 additionalProperties: false
  39             }
  40         ],
  41
  42         messages: {
  43             nativeReassign: "Read-only global '{{name}}' should not be modified."
  44         }
  45     },
  46
  47     create(context) {
  48         const config = context.options[0];
  49         const exceptions = (config && config.exceptions) || [];
  50
  51         /**
  52          * Reports write references.
  53          * @param {Reference} reference A reference to check.
  54          * @param {int} index The index of the reference in the references.
  55          * @param {Reference[]} references The array that the reference belongs to.
  56          * @returns {void}
  57          */
  58         function checkReference(reference, index, references) {
  59             const identifier = reference.identifier;
  60
  61             if (reference.init === false &&
  62                 reference.isWrite() &&
  63
  64                 /*
  65                  * Destructuring assignments can have multiple default value,
  66                  * so possibly there are multiple writeable references for the same identifier.
  67                  */
  68                 (index === 0 || references[index - 1].identifier !== identifier)
  69             ) {
  70                 context.report({
  71                     node: identifier,
  72                     messageId: "nativeReassign",
  73                     data: identifier
  74                 });
  75             }
  76         }
  77
  78         /**
  79          * Reports write references if a given variable is read-only builtin.
  80          * @param {Variable} variable A variable to check.
  81          * @returns {void}
  82          */
  83         function checkVariable(variable) {
  84             if (variable.writeable === false && exceptions.indexOf(variable.name) === -1) {
  85                 variable.references.forEach(checkReference);
  86             }
  87         }
  88
  89         return {
  90             Program() {
  91                 const globalScope = context.getScope();
  92
  93                 globalScope.variables.forEach(checkVariable);
  94             }
  95         };
  96     }
  97 };