eslint/lib/rules/prefer-object-has-own.js

   1 /**
   2  * @fileoverview Prefers Object.hasOwn() instead of Object.prototype.hasOwnProperty.call()
   3  * @author Nitin Kumar
   4  * @author Gautam Arora
   5  */
   6
   7 "use strict";
   8
   9 //------------------------------------------------------------------------------
  10 // Requirements
  11 //------------------------------------------------------------------------------
  12
  13 const astUtils = require("./utils/ast-utils");
  14
  15 //------------------------------------------------------------------------------
  16 // Helpers
  17 //------------------------------------------------------------------------------
  18
  19 /**
  20  * Checks if the given node is considered to be an access to a property of `Object.prototype`.
  21  * @param {ASTNode} node `MemberExpression` node to evaluate.
  22  * @returns {boolean} `true` if `node.object` is `Object`, `Object.prototype`, or `{}` (empty 'ObjectExpression' node).
  23  */
  24 function hasLeftHandObject(node) {
  25
  26     /*
  27      * ({}).hasOwnProperty.call(obj, prop) - `true`
  28      * ({ foo }.hasOwnProperty.call(obj, prop)) - `false`, object literal should be empty
  29      */
  30     if (node.object.type === "ObjectExpression" && node.object.properties.length === 0) {
  31         return true;
  32     }
  33
  34     const objectNodeToCheck = node.object.type === "MemberExpression" && astUtils.getStaticPropertyName(node.object) === "prototype" ? node.object.object : node.object;
  35
  36     if (objectNodeToCheck.type === "Identifier" && objectNodeToCheck.name === "Object") {
  37         return true;
  38     }
  39
  40     return false;
  41 }
  42
  43 //------------------------------------------------------------------------------
  44 // Rule Definition
  45 //------------------------------------------------------------------------------
  46
  47 /** @type {import('../shared/types').Rule} */
  48 module.exports = {
  49     meta: {
  50         type: "suggestion",
  51         docs: {
  52             description:
  53                 "Disallow use of `Object.prototype.hasOwnProperty.call()` and prefer use of `Object.hasOwn()`",
  54             recommended: false,
  55             url: "https://eslint.org/docs/latest/rules/prefer-object-has-own"
  56         },
  57         schema: [],
  58         messages: {
  59             useHasOwn: "Use 'Object.hasOwn()' instead of 'Object.prototype.hasOwnProperty.call()'."
  60         },
  61         fixable: "code"
  62     },
  63     create(context) {
  64
  65         const sourceCode = context.sourceCode;
  66
  67         return {
  68             CallExpression(node) {
  69                 if (!(node.callee.type === "MemberExpression" && node.callee.object.type === "MemberExpression")) {
  70                     return;
  71                 }
  72
  73                 const calleePropertyName = astUtils.getStaticPropertyName(node.callee);
  74                 const objectPropertyName = astUtils.getStaticPropertyName(node.callee.object);
  75                 const isObject = hasLeftHandObject(node.callee.object);
  76
  77                 // check `Object` scope
  78                 const scope = sourceCode.getScope(node);
  79                 const variable = astUtils.getVariableByName(scope, "Object");
  80
  81                 if (
  82                     calleePropertyName === "call" &&
  83                     objectPropertyName === "hasOwnProperty" &&
  84                     isObject &&
  85                     variable && variable.scope.type === "global"
  86                 ) {
  87                     context.report({
  88                         node,
  89                         messageId: "useHasOwn",
  90                         fix(fixer) {
  91
  92                             if (sourceCode.getCommentsInside(node.callee).length > 0) {
  93                                 return null;
  94                             }
  95
  96                             const tokenJustBeforeNode = sourceCode.getTokenBefore(node.callee, { includeComments: true });
  97
  98                             // for https://github.com/eslint/eslint/pull/15346#issuecomment-991417335
  99                             if (
 100                                 tokenJustBeforeNode &&
 101                                 tokenJustBeforeNode.range[1] === node.callee.range[0] &&
 102                                 !astUtils.canTokensBeAdjacent(tokenJustBeforeNode, "Object.hasOwn")
 103                             ) {
 104                                 return fixer.replaceText(node.callee, " Object.hasOwn");
 105                             }
 106
 107                             return fixer.replaceText(node.callee, "Object.hasOwn");
 108                         }
 109                     });
 110                 }
 111             }
 112         };
 113     }
 114 };