In The Flow
A user submits a form, and React sends the data to the server using this type of HTTP request.
What is a POST request?
You choose this React pattern so the component always controls form values and validation.
What is a controlled component?
Your first stop for checking whether the frontend is actually calling the API.
What is the browser Network tab?
This JavaScript concept represents a value that will exist in the future.
What is a promise?
You describe an API as this to a non-technical teammate.
What is a waiter between the client and the kitchen?
After the server processes a request successfully, it sends this format back to the client to update the UI.
What is a JSON response?
You use this instead of fetch because it simplifies JSON handling and error responses.
What is Axios?
You add these temporarily to trace values through your app.
What are console logs?
This syntax makes async code read like synchronous code.
What is async/await?
You explain CORS as a browser rule that controls this.
What is which frontends are allowed to talk to an API?
This React hook is commonly used to fetch data when a component first loads
What is useEffect?
You centralize this logic in Express so all routes handle failures consistently.
What is centralized error-handling middleware?
A 404 error usually means this is wrong or missing.
What is the API route or endpoint?
This Node.js feature allows the server to handle many requests without blocking.
What is the event loop?
You describe middleware as logic that runs in this position.
What is between the request and the response?
This is the full flow of a MERN request: React → Express → MongoDB → back to React.
What is the client–server request/response lifecycle?
You pick MongoDB over SQL because your data is flexible and JSON-based.
What is a NoSQL database?
A 500 error tells you this layer failed.
What is the server or backend?
Database calls and API requests are examples of this type of operation.
What are examples of common asynchronous operations?
You emphasize this when discussing security practices.
What is reducing the attack surface?
An interviewer asks you to explain what happens from clicking “Submit” to seeing a success message.
What is walking through the full front-end to back-end data flow?
An interviewer asks why you separated routes, controllers, and models in your API.
What is code organization for maintainability and scalability?
Your debugging strategy involves checking UI, network, then server logs in order.
What is isolating the problem by layers?
An interviewer asks why async code is essential in a web server.
What is preventing the server from blocking while waiting for operations like querying a database?
An interviewer cares less about perfection and more about this when you answer.
What is clear, structured reasoning?