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     skipChainExpression
  15 } = require("./utils/ast-utils");
  16
  17 //------------------------------------------------------------------------------
  18 // Helpers
  19 //------------------------------------------------------------------------------
  20
  21 /**
  22  * Checks if the given name is a prohibited identifier.
  23  * @param {string} name The name to check
  24  * @returns {boolean} Whether or not the name is prohibited.
  25  */
  26 function isProhibitedIdentifier(name) {
  27     return /^(alert|confirm|prompt)$/u.test(name);
  28 }
  29
  30 /**
  31  * Finds the eslint-scope reference in the given scope.
  32  * @param {Object} scope The scope to search.
  33  * @param {ASTNode} node The identifier node.
  34  * @returns {Reference|null} Returns the found reference or null if none were found.
  35  */
  36 function findReference(scope, node) {
  37     const references = scope.references.filter(reference => reference.identifier.range[0] === node.range[0] &&
  38             reference.identifier.range[1] === node.range[1]);
  39
  40     if (references.length === 1) {
  41         return references[0];
  42     }
  43     return null;
  44 }
  45
  46 /**
  47  * Checks if the given identifier node is shadowed in the given scope.
  48  * @param {Object} scope The current scope.
  49  * @param {string} node The identifier node to check
  50  * @returns {boolean} Whether or not the name is shadowed.
  51  */
  52 function isShadowed(scope, node) {
  53     const reference = findReference(scope, node);
  54
  55     return reference && reference.resolved && reference.resolved.defs.length > 0;
  56 }
  57
  58 /**
  59  * Checks if the given identifier node is a ThisExpression in the global scope or the global window property.
  60  * @param {Object} scope The current scope.
  61  * @param {string} node The identifier node to check
  62  * @returns {boolean} Whether or not the node is a reference to the global object.
  63  */
  64 function isGlobalThisReferenceOrGlobalWindow(scope, node) {
  65     if (scope.type === "global" && node.type === "ThisExpression") {
  66         return true;
  67     }
  68     if (
  69         node.type === "Identifier" &&
  70         (
  71             node.name === "window" ||
  72             (node.name === "globalThis" && getVariableByName(scope, "globalThis"))
  73         )
  74     ) {
  75         return !isShadowed(scope, node);
  76     }
  77
  78     return false;
  79 }
  80
  81 //------------------------------------------------------------------------------
  82 // Rule Definition
  83 //------------------------------------------------------------------------------
  84
  85 /** @type {import('../shared/types').Rule} */
  86 module.exports = {
  87     meta: {
  88         type: "suggestion",
  89
  90         docs: {
  91             description: "disallow the use of `alert`, `confirm`, and `prompt`",
  92             recommended: false,
  93             url: "https://eslint.org/docs/rules/no-alert"
  94         },
  95
  96         schema: [],
  97
  98         messages: {
  99             unexpected: "Unexpected {{name}}."
 100         }
 101     },
 102
 103     create(context) {
 104         return {
 105             CallExpression(node) {
 106                 const callee = skipChainExpression(node.callee),
 107                     currentScope = context.getScope();
 108
 109                 // without window.
 110                 if (callee.type === "Identifier") {
 111                     const name = callee.name;
 112
 113                     if (!isShadowed(currentScope, callee) && isProhibitedIdentifier(callee.name)) {
 114                         context.report({
 115                             node,
 116                             messageId: "unexpected",
 117                             data: { name }
 118                         });
 119                     }
 120
 121                 } else if (callee.type === "MemberExpression" && isGlobalThisReferenceOrGlobalWindow(currentScope, callee.object)) {
 122                     const name = getPropertyName(callee);
 123
 124                     if (isProhibitedIdentifier(name)) {
 125                         context.report({
 126                             node,
 127                             messageId: "unexpected",
 128                             data: { name }
 129                         });
 130                     }
 131                 }
 132             }
 133         };
 134
 135     }
 136 };