eslint/lib/rules/no-catch-shadow.js

   1 /**
   2  * @fileoverview Rule to flag variable leak in CatchClauses in IE 8 and earlier
   3  * @author Ian Christian Myers
   4  * @deprecated in ESLint v5.1.0
   5  */
   6
   7 "use strict";
   8
   9 //------------------------------------------------------------------------------
  10 // Requirements
  11 //------------------------------------------------------------------------------
  12
  13 const astUtils = require("./utils/ast-utils");
  14
  15 //------------------------------------------------------------------------------
  16 // Rule Definition
  17 //------------------------------------------------------------------------------
  18
  19 /** @type {import('../shared/types').Rule} */
  20 module.exports = {
  21     meta: {
  22         type: "suggestion",
  23
  24         docs: {
  25             description: "Disallow `catch` clause parameters from shadowing variables in the outer scope",
  26             recommended: false,
  27             url: "https://eslint.org/docs/latest/rules/no-catch-shadow"
  28         },
  29
  30         replacedBy: ["no-shadow"],
  31
  32         deprecated: true,
  33         schema: [],
  34
  35         messages: {
  36             mutable: "Value of '{{name}}' may be overwritten in IE 8 and earlier."
  37         }
  38     },
  39
  40     create(context) {
  41
  42         const sourceCode = context.sourceCode;
  43
  44         //--------------------------------------------------------------------------
  45         // Helpers
  46         //--------------------------------------------------------------------------
  47
  48         /**
  49          * Check if the parameters are been shadowed
  50          * @param {Object} scope current scope
  51          * @param {string} name parameter name
  52          * @returns {boolean} True is its been shadowed
  53          */
  54         function paramIsShadowing(scope, name) {
  55             return astUtils.getVariableByName(scope, name) !== null;
  56         }
  57
  58         //--------------------------------------------------------------------------
  59         // Public API
  60         //--------------------------------------------------------------------------
  61
  62         return {
  63
  64             "CatchClause[param!=null]"(node) {
  65                 let scope = sourceCode.getScope(node);
  66
  67                 /*
  68                  * When ecmaVersion >= 6, CatchClause creates its own scope
  69                  * so start from one upper scope to exclude the current node
  70                  */
  71                 if (scope.block === node) {
  72                     scope = scope.upper;
  73                 }
  74
  75                 if (paramIsShadowing(scope, node.param.name)) {
  76                     context.report({ node, messageId: "mutable", data: { name: node.param.name } });
  77                 }
  78             }
  79         };
  80
  81     }
  82 };