solium-plugin-security/rules/no-unreachable-code.js

Official Solium Plugin for Security-related lint rules

/**
 * @fileoverview Disallow unreachable code
 * @author Beau Gunderson <beau@beaugunderson.com>
 */

"use strict";

module.exports = {
    meta: {
        docs: {
            recommended: true,
            type: "error",
            description: "Disallow unreachable code"
        },

        schema: []
    },

    create: function(context) {
        function inspectFunctionDeclaration(emitted) {
            const { node } = emitted;

            // Exit now if function is abstract (has no body)
            if (emitted.exit || node.is_abstract) {
                return;
            }

            let topLevelStatements = node.body.body;
            let lastIndex = topLevelStatements.length - 1;

            let firstTopLevelReturnIndex = topLevelStatements.findIndex(
                statement => statement.type === "ReturnStatement"
            );

            if (firstTopLevelReturnIndex === -1) {
                return;
            }

            if (firstTopLevelReturnIndex !== lastIndex) {
                context.report({
                    node: topLevelStatements[firstTopLevelReturnIndex + 1],
                    message: "Code is unreachable."
                });
            }
        }

        return {
            FunctionDeclaration: inspectFunctionDeclaration
        };
    }
};