eslint/lib/rules/no-label-var.js

   1 /**
   2  * @fileoverview Rule to flag labels that are the same as an identifier
   3  * @author Ian Christian Myers
   4  */
   5
   6 "use strict";
   7
   8 //------------------------------------------------------------------------------
   9 // Requirements
  10 //------------------------------------------------------------------------------
  11
  12 const astUtils = require("./utils/ast-utils");
  13
  14 //------------------------------------------------------------------------------
  15 // Rule Definition
  16 //------------------------------------------------------------------------------
  17
  18 /** @type {import('../shared/types').Rule} */
  19 module.exports = {
  20     meta: {
  21         type: "suggestion",
  22
  23         docs: {
  24             description: "Disallow labels that share a name with a variable",
  25             recommended: false,
  26             url: "https://eslint.org/docs/rules/no-label-var"
  27         },
  28
  29         schema: [],
  30
  31         messages: {
  32             identifierClashWithLabel: "Found identifier with same name as label."
  33         }
  34     },
  35
  36     create(context) {
  37
  38         //--------------------------------------------------------------------------
  39         // Helpers
  40         //--------------------------------------------------------------------------
  41
  42         /**
  43          * Check if the identifier is present inside current scope
  44          * @param {Object} scope current scope
  45          * @param {string} name To evaluate
  46          * @returns {boolean} True if its present
  47          * @private
  48          */
  49         function findIdentifier(scope, name) {
  50             return astUtils.getVariableByName(scope, name) !== null;
  51         }
  52
  53         //--------------------------------------------------------------------------
  54         // Public API
  55         //--------------------------------------------------------------------------
  56
  57         return {
  58
  59             LabeledStatement(node) {
  60
  61                 // Fetch the innermost scope.
  62                 const scope = context.getScope();
  63
  64                 /*
  65                  * Recursively find the identifier walking up the scope, starting
  66                  * with the innermost scope.
  67                  */
  68                 if (findIdentifier(scope, node.label.name)) {
  69                     context.report({
  70                         node,
  71                         messageId: "identifierClashWithLabel"
  72                     });
  73                 }
  74             }
  75
  76         };
  77
  78     }
  79 };