Check out example codes for "Property 'isAuth' does not exist on type 'Request<ParamsDictionary, any, any, ParsedQs>'". It will help you in understanding the concepts better.

Code Example 1

// create file custom.d.ts and declare the following

declare namespace Express {
  export interface Request {
      user: any;
  }
  export interface Response {
      user: any;
  }
}

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