eslint/lib/rules/max-params.js

   1 /**
   2  * @fileoverview Rule to flag when a function has too many parameters
   3  * @author Ilya Volodin
   4  */
   5
   6 "use strict";
   7
   8 //------------------------------------------------------------------------------
   9 // Requirements
  10 //------------------------------------------------------------------------------
  11
  12 const astUtils = require("./utils/ast-utils");
  13 const { upperCaseFirst } = require("../shared/string-utils");
  14
  15 //------------------------------------------------------------------------------
  16 // Rule Definition
  17 //------------------------------------------------------------------------------
  18
  19 /** @type {import('../shared/types').Rule} */
  20 module.exports = {
  21     meta: {
  22         type: "suggestion",
  23
  24         docs: {
  25             description: "Enforce a maximum number of parameters in function definitions",
  26             recommended: false,
  27             url: "https://eslint.org/docs/rules/max-params"
  28         },
  29
  30         schema: [
  31             {
  32                 oneOf: [
  33                     {
  34                         type: "integer",
  35                         minimum: 0
  36                     },
  37                     {
  38                         type: "object",
  39                         properties: {
  40                             maximum: {
  41                                 type: "integer",
  42                                 minimum: 0
  43                             },
  44                             max: {
  45                                 type: "integer",
  46                                 minimum: 0
  47                             }
  48                         },
  49                         additionalProperties: false
  50                     }
  51                 ]
  52             }
  53         ],
  54         messages: {
  55             exceed: "{{name}} has too many parameters ({{count}}). Maximum allowed is {{max}}."
  56         }
  57     },
  58
  59     create(context) {
  60         const sourceCode = context.getSourceCode();
  61         const option = context.options[0];
  62         let numParams = 3;
  63
  64         if (
  65             typeof option === "object" &&
  66             (Object.prototype.hasOwnProperty.call(option, "maximum") || Object.prototype.hasOwnProperty.call(option, "max"))
  67         ) {
  68             numParams = option.maximum || option.max;
  69         }
  70         if (typeof option === "number") {
  71             numParams = option;
  72         }
  73
  74         /**
  75          * Checks a function to see if it has too many parameters.
  76          * @param {ASTNode} node The node to check.
  77          * @returns {void}
  78          * @private
  79          */
  80         function checkFunction(node) {
  81             if (node.params.length > numParams) {
  82                 context.report({
  83                     loc: astUtils.getFunctionHeadLoc(node, sourceCode),
  84                     node,
  85                     messageId: "exceed",
  86                     data: {
  87                         name: upperCaseFirst(astUtils.getFunctionNameWithKind(node)),
  88                         count: node.params.length,
  89                         max: numParams
  90                     }
  91                 });
  92             }
  93         }
  94
  95         return {
  96             FunctionDeclaration: checkFunction,
  97             ArrowFunctionExpression: checkFunction,
  98             FunctionExpression: checkFunction
  99         };
 100
 101     }
 102 };