eslint/lib/rules/radix.js

   1 /**
   2  * @fileoverview Rule to flag use of parseInt without a radix argument
   3  * @author James Allardice
   4  */
   5
   6 "use strict";
   7
   8 //------------------------------------------------------------------------------
   9 // Requirements
  10 //------------------------------------------------------------------------------
  11
  12 const astUtils = require("./utils/ast-utils");
  13
  14 //------------------------------------------------------------------------------
  15 // Helpers
  16 //------------------------------------------------------------------------------
  17
  18 const MODE_ALWAYS = "always",
  19     MODE_AS_NEEDED = "as-needed";
  20
  21 const validRadixValues = new Set(Array.from({ length: 37 - 2 }, (_, index) => index + 2));
  22
  23 /**
  24  * Checks whether a given variable is shadowed or not.
  25  * @param {eslint-scope.Variable} variable A variable to check.
  26  * @returns {boolean} `true` if the variable is shadowed.
  27  */
  28 function isShadowed(variable) {
  29     return variable.defs.length >= 1;
  30 }
  31
  32 /**
  33  * Checks whether a given node is a MemberExpression of `parseInt` method or not.
  34  * @param {ASTNode} node A node to check.
  35  * @returns {boolean} `true` if the node is a MemberExpression of `parseInt`
  36  *      method.
  37  */
  38 function isParseIntMethod(node) {
  39     return (
  40         node.type === "MemberExpression" &&
  41         !node.computed &&
  42         node.property.type === "Identifier" &&
  43         node.property.name === "parseInt"
  44     );
  45 }
  46
  47 /**
  48  * Checks whether a given node is a valid value of radix or not.
  49  *
  50  * The following values are invalid.
  51  *
  52  * - A literal except integers between 2 and 36.
  53  * - undefined.
  54  * @param {ASTNode} radix A node of radix to check.
  55  * @returns {boolean} `true` if the node is valid.
  56  */
  57 function isValidRadix(radix) {
  58     return !(
  59         (radix.type === "Literal" && !validRadixValues.has(radix.value)) ||
  60         (radix.type === "Identifier" && radix.name === "undefined")
  61     );
  62 }
  63
  64 /**
  65  * Checks whether a given node is a default value of radix or not.
  66  * @param {ASTNode} radix A node of radix to check.
  67  * @returns {boolean} `true` if the node is the literal node of `10`.
  68  */
  69 function isDefaultRadix(radix) {
  70     return radix.type === "Literal" && radix.value === 10;
  71 }
  72
  73 //------------------------------------------------------------------------------
  74 // Rule Definition
  75 //------------------------------------------------------------------------------
  76
  77 module.exports = {
  78     meta: {
  79         type: "suggestion",
  80
  81         docs: {
  82             description: "enforce the consistent use of the radix argument when using `parseInt()`",
  83             category: "Best Practices",
  84             recommended: false,
  85             url: "https://eslint.org/docs/rules/radix",
  86             suggestion: true
  87         },
  88
  89         schema: [
  90             {
  91                 enum: ["always", "as-needed"]
  92             }
  93         ],
  94
  95         messages: {
  96             missingParameters: "Missing parameters.",
  97             redundantRadix: "Redundant radix parameter.",
  98             missingRadix: "Missing radix parameter.",
  99             invalidRadix: "Invalid radix parameter, must be an integer between 2 and 36.",
 100             addRadixParameter10: "Add radix parameter `10` for parsing decimal numbers."
 101         }
 102     },
 103
 104     create(context) {
 105         const mode = context.options[0] || MODE_ALWAYS;
 106
 107         /**
 108          * Checks the arguments of a given CallExpression node and reports it if it
 109          * offends this rule.
 110          * @param {ASTNode} node A CallExpression node to check.
 111          * @returns {void}
 112          */
 113         function checkArguments(node) {
 114             const args = node.arguments;
 115
 116             switch (args.length) {
 117                 case 0:
 118                     context.report({
 119                         node,
 120                         messageId: "missingParameters"
 121                     });
 122                     break;
 123
 124                 case 1:
 125                     if (mode === MODE_ALWAYS) {
 126                         context.report({
 127                             node,
 128                             messageId: "missingRadix",
 129                             suggest: [
 130                                 {
 131                                     messageId: "addRadixParameter10",
 132                                     fix(fixer) {
 133                                         const sourceCode = context.getSourceCode();
 134                                         const tokens = sourceCode.getTokens(node);
 135                                         const lastToken = tokens[tokens.length - 1]; // Parenthesis.
 136                                         const secondToLastToken = tokens[tokens.length - 2]; // May or may not be a comma.
 137                                         const hasTrailingComma = secondToLastToken.type === "Punctuator" && secondToLastToken.value === ",";
 138
 139                                         return fixer.insertTextBefore(lastToken, hasTrailingComma ? " 10," : ", 10");
 140                                     }
 141                                 }
 142                             ]
 143                         });
 144                     }
 145                     break;
 146
 147                 default:
 148                     if (mode === MODE_AS_NEEDED && isDefaultRadix(args[1])) {
 149                         context.report({
 150                             node,
 151                             messageId: "redundantRadix"
 152                         });
 153                     } else if (!isValidRadix(args[1])) {
 154                         context.report({
 155                             node,
 156                             messageId: "invalidRadix"
 157                         });
 158                     }
 159                     break;
 160             }
 161         }
 162
 163         return {
 164             "Program:exit"() {
 165                 const scope = context.getScope();
 166                 let variable;
 167
 168                 // Check `parseInt()`
 169                 variable = astUtils.getVariableByName(scope, "parseInt");
 170                 if (variable && !isShadowed(variable)) {
 171                     variable.references.forEach(reference => {
 172                         const node = reference.identifier;
 173
 174                         if (astUtils.isCallee(node)) {
 175                             checkArguments(node.parent);
 176                         }
 177                     });
 178                 }
 179
 180                 // Check `Number.parseInt()`
 181                 variable = astUtils.getVariableByName(scope, "Number");
 182                 if (variable && !isShadowed(variable)) {
 183                     variable.references.forEach(reference => {
 184                         const node = reference.identifier.parent;
 185                         const maybeCallee = node.parent.type === "ChainExpression"
 186                             ? node.parent
 187                             : node;
 188
 189                         if (isParseIntMethod(node) && astUtils.isCallee(maybeCallee)) {
 190                             checkArguments(maybeCallee.parent);
 191                         }
 192                     });
 193                 }
 194             }
 195         };
 196     }
 197 };