node/tools/eslint/lib/rules/max-params.js

/**
 * @fileoverview Rule to flag when a function has too many parameters
 * @author Ilya Volodin
 * @copyright 2014 Nicholas C. Zakas. All rights reserved.
 * @copyright 2013 Ilya Volodin. All rights reserved.
 */

"use strict";

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

module.exports = function(context) {

    var option = context.options[0],
        numParams = 3;

    if (typeof option === "object" && option.hasOwnProperty("maximum") && typeof option.maximum === "number") {
        numParams = option.maximum;
    }
    if (typeof option === "object" && option.hasOwnProperty("max") && typeof option.max === "number") {
        numParams = option.max;
    }
    if (typeof option === "number") {
        numParams = option;
    }

    /**
     * Checks a function to see if it has too many parameters.
     * @param {ASTNode} node The node to check.
     * @returns {void}
     * @private
     */
    function checkFunction(node) {
        if (node.params.length > numParams) {
            context.report(node, "This function has too many parameters ({{count}}). Maximum allowed is {{max}}.", {
                count: node.params.length,
                max: numParams
            });
        }
    }

    return {
        "FunctionDeclaration": checkFunction,
        "ArrowFunctionExpression": checkFunction,
        "FunctionExpression": checkFunction
    };

};

module.exports.schema = [
    {
        "oneOf": [
            {
                "type": "integer",
                "minimum": 0
            },
            {
                "type": "object",
                "properties": {
                    "maximum": {
                        "type": "integer",
                        "minimum": 0
                    },
                    "max": {
                        "type": "integer",
                        "minimum": 0
                    }
                },
                "additionalProperties": false
            }
        ]
    }
];