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