eslint/lib/rules/no-obj-calls.js

   1 /**
   2  * @fileoverview Rule to flag use of an object property of the global object (Math and JSON) as a function
   3  * @author James Allardice
   4  */
   5
   6 "use strict";
   7
   8 //------------------------------------------------------------------------------
   9 // Requirements
  10 //------------------------------------------------------------------------------
  11
  12 const { CALL, CONSTRUCT, ReferenceTracker } = require("eslint-utils");
  13 const getPropertyName = require("./utils/ast-utils").getStaticPropertyName;
  14
  15 //------------------------------------------------------------------------------
  16 // Helpers
  17 //------------------------------------------------------------------------------
  18
  19 const nonCallableGlobals = ["Atomics", "JSON", "Math", "Reflect"];
  20
  21 /**
  22  * Returns the name of the node to report
  23  * @param {ASTNode} node A node to report
  24  * @returns {string} name to report
  25  */
  26 function getReportNodeName(node) {
  27     if (node.type === "ChainExpression") {
  28         return getReportNodeName(node.expression);
  29     }
  30     if (node.type === "MemberExpression") {
  31         return getPropertyName(node);
  32     }
  33     return node.name;
  34 }
  35
  36 //------------------------------------------------------------------------------
  37 // Rule Definition
  38 //------------------------------------------------------------------------------
  39
  40 module.exports = {
  41     meta: {
  42         type: "problem",
  43
  44         docs: {
  45             description: "disallow calling global object properties as functions",
  46             category: "Possible Errors",
  47             recommended: true,
  48             url: "https://eslint.org/docs/rules/no-obj-calls"
  49         },
  50
  51         schema: [],
  52
  53         messages: {
  54             unexpectedCall: "'{{name}}' is not a function.",
  55             unexpectedRefCall: "'{{name}}' is reference to '{{ref}}', which is not a function."
  56         }
  57     },
  58
  59     create(context) {
  60
  61         return {
  62             Program() {
  63                 const scope = context.getScope();
  64                 const tracker = new ReferenceTracker(scope);
  65                 const traceMap = {};
  66
  67                 for (const g of nonCallableGlobals) {
  68                     traceMap[g] = {
  69                         [CALL]: true,
  70                         [CONSTRUCT]: true
  71                     };
  72                 }
  73
  74                 for (const { node, path } of tracker.iterateGlobalReferences(traceMap)) {
  75                     const name = getReportNodeName(node.callee);
  76                     const ref = path[0];
  77                     const messageId = name === ref ? "unexpectedCall" : "unexpectedRefCall";
  78
  79                     context.report({ node, messageId, data: { name, ref } });
  80                 }
  81             }
  82         };
  83     }
  84 };