The primary role of middleware in Express.js is to manage HTTP requests and responses. Middleware functions are executed in the order they are defined in the Express application and can perform various tasks such as authentication, logging, and modifying request/response objects. They play a crucial role in the request/response cycle.

In JavaScript, the export keyword is used to export multiple things from a module. It allows you to specify which functions, objects, or variables should be accessible from outside the module. The import keyword is used for importing from modules, not exporting. The require and module keywords are used in CommonJS, a different module system.

In an Express.js project, it's a best practice to store your static files like images, CSS, and JavaScript in a dedicated static directory. This helps organize your project and makes it clear which files are intended to be served statically. Storing them in the project root, node_modules, or a database is not a recommended practice for serving static files.

JavaScript allows circular dependencies, but it ensures that each module is only executed once. This is achieved through a mechanism called "module caching."

When an uncaught error occurs in an async function, the returned Promise will be in a "Rejected" state. In the Promise lifecycle, it can start as "Pending," move to "Fulfilled" upon success, or "Rejected" upon an error.

The global object in Node.js can be used to store data that needs to be shared between different Node.js modules. It acts as a global namespace for variables and allows you to share data across different parts of your application. The other options do not accurately describe the common use case for the global object.

Semantic versioning allows pre-release versions to be denoted with a hyphen, followed by additional labels and numbers, and build metadata is indicated with a plus sign. This is essential for managing versions during development and testing phases.

In JavaScript, the string data type is used to store a sequence of characters. The char data type doesn't exist in JavaScript, and neither sequence nor text are valid data types for this purpose.

In Node.js, when an error occurs, the error object is typically an instance of the built-in Error object. This object contains valuable information about the error, such as a message and a stack trace.

The extends property in an ESLint configuration file allows you to inherit configurations from other configurations. It's a way to reuse or build upon existing ESLint configurations, making it easier to enforce consistent coding standards across projects.