eslint/lib/rules/no-alert.js

   1 /**
   2  * @fileoverview Rule to flag use of alert, confirm, prompt
   3  * @author Nicholas C. Zakas
   4  */
   5 "use strict";
   6
   7 //------------------------------------------------------------------------------
   8 // Requirements
   9 //------------------------------------------------------------------------------
  10
  11 const {
  12     getStaticPropertyName: getPropertyName,
  13     getVariableByName
  14 } = require("./utils/ast-utils");
  15
  16 //------------------------------------------------------------------------------
  17 // Helpers
  18 //------------------------------------------------------------------------------
  19
  20 /**
  21  * Checks if the given name is a prohibited identifier.
  22  * @param {string} name The name to check
  23  * @returns {boolean} Whether or not the name is prohibited.
  24  */
  25 function isProhibitedIdentifier(name) {
  26     return /^(alert|confirm|prompt)$/u.test(name);
  27 }
  28
  29 /**
  30  * Finds the eslint-scope reference in the given scope.
  31  * @param {Object} scope The scope to search.
  32  * @param {ASTNode} node The identifier node.
  33  * @returns {Reference|null} Returns the found reference or null if none were found.
  34  */
  35 function findReference(scope, node) {
  36     const references = scope.references.filter(reference => reference.identifier.range[0] === node.range[0] &&
  37             reference.identifier.range[1] === node.range[1]);
  38
  39     if (references.length === 1) {
  40         return references[0];
  41     }
  42     return null;
  43 }
  44
  45 /**
  46  * Checks if the given identifier node is shadowed in the given scope.
  47  * @param {Object} scope The current scope.
  48  * @param {string} node The identifier node to check
  49  * @returns {boolean} Whether or not the name is shadowed.
  50  */
  51 function isShadowed(scope, node) {
  52     const reference = findReference(scope, node);
  53
  54     return reference && reference.resolved && reference.resolved.defs.length > 0;
  55 }
  56
  57 /**
  58  * Checks if the given identifier node is a ThisExpression in the global scope or the global window property.
  59  * @param {Object} scope The current scope.
  60  * @param {string} node The identifier node to check
  61  * @returns {boolean} Whether or not the node is a reference to the global object.
  62  */
  63 function isGlobalThisReferenceOrGlobalWindow(scope, node) {
  64     if (scope.type === "global" && node.type === "ThisExpression") {
  65         return true;
  66     }
  67     if (node.name === "window" || (node.name === "globalThis" && getVariableByName(scope, "globalThis"))) {
  68         return !isShadowed(scope, node);
  69     }
  70
  71     return false;
  72 }
  73
  74 //------------------------------------------------------------------------------
  75 // Rule Definition
  76 //------------------------------------------------------------------------------
  77
  78 module.exports = {
  79     meta: {
  80         type: "suggestion",
  81
  82         docs: {
  83             description: "disallow the use of `alert`, `confirm`, and `prompt`",
  84             category: "Best Practices",
  85             recommended: false,
  86             url: "https://eslint.org/docs/rules/no-alert"
  87         },
  88
  89         schema: [],
  90
  91         messages: {
  92             unexpected: "Unexpected {{name}}."
  93         }
  94     },
  95
  96     create(context) {
  97         return {
  98             CallExpression(node) {
  99                 const callee = node.callee,
 100                     currentScope = context.getScope();
 101
 102                 // without window.
 103                 if (callee.type === "Identifier") {
 104                     const name = callee.name;
 105
 106                     if (!isShadowed(currentScope, callee) && isProhibitedIdentifier(callee.name)) {
 107                         context.report({
 108                             node,
 109                             messageId: "unexpected",
 110                             data: { name }
 111                         });
 112                     }
 113
 114                 } else if (callee.type === "MemberExpression" && isGlobalThisReferenceOrGlobalWindow(currentScope, callee.object)) {
 115                     const name = getPropertyName(callee);
 116
 117                     if (isProhibitedIdentifier(name)) {
 118                         context.report({
 119                             node,
 120                             messageId: "unexpected",
 121                             data: { name }
 122                         });
 123                     }
 124                 }
 125             }
 126         };
 127
 128     }
 129 };