eslint/lib/rules/no-catch-shadow.js

/**
 * @fileoverview Rule to flag variable leak in CatchClauses in IE 8 and earlier
 * @author Ian Christian Myers
 */

"use strict";

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

var astUtils = require("../ast-utils");

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

module.exports = function(context) {

    //--------------------------------------------------------------------------
    // Helpers
    //--------------------------------------------------------------------------

    /**
     * Check if the parameters are been shadowed
     * @param {object} scope current scope
     * @param {string} name parameter name
     * @returns {boolean} True is its been shadowed
     */
    function paramIsShadowing(scope, name) {
        return astUtils.getVariableByName(scope, name) !== null;
    }

    //--------------------------------------------------------------------------
    // Public API
    //--------------------------------------------------------------------------

    return {

        "CatchClause": function(node) {
            var scope = context.getScope();

            // When blockBindings is enabled, CatchClause creates its own scope
            // so start from one upper scope to exclude the current node
            if (scope.block === node) {
                scope = scope.upper;
            }

            if (paramIsShadowing(scope, node.param.name)) {
                context.report(node, "Value of '{{name}}' may be overwritten in IE 8 and earlier.",
                        { name: node.param.name });
            }
        }
    };

};

module.exports.schema = [];