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no-dupe-args.js 2.29 KiB
/**
 * @fileoverview Rule to flag duplicate arguments
 * @author Jamund Ferguson
 */
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
    meta: {
        type: "problem",
        docs: {
            description: "disallow duplicate arguments in `function` definitions",
            category: "Possible Errors",
            recommended: true,
            url: "https://eslint.org/docs/rules/no-dupe-args"
        schema: [],
        messages: {
            unexpected: "Duplicate param '{{name}}'."
    create(context) {
        //--------------------------------------------------------------------------
        // Helpers
        //--------------------------------------------------------------------------
        /**
         * Checks whether or not a given definition is a parameter's.
         * @param {eslint-scope.DefEntry} def A definition to check.
         * @returns {boolean} `true` if the definition is a parameter's.
        function isParameter(def) {
            return def.type === "Parameter";
        /**
         * Determines if a given node has duplicate parameters.
         * @param {ASTNode} node The node to check.
         * @returns {void}
         * @private
        function checkParams(node) {
            const variables = context.getDeclaredVariables(node);
            for (let i = 0; i < variables.length; ++i) {
                const variable = variables[i];
                // Checks and reports duplications.
                const defs = variable.defs.filter(isParameter);
                if (defs.length >= 2) {
                    context.report({
                        node,
                        messageId: "unexpected",
                        data: { name: variable.name }
                    });
        //--------------------------------------------------------------------------
// Public API //-------------------------------------------------------------------------- return { FunctionDeclaration: checkParams, FunctionExpression: checkParams }; } };