Router updating performance model
Otherwise, the router treats "/foo" and "/foo/" as the same.headers are easily spoofed and the detected IP addresses are unreliable.The “extended” syntax allows for rich objects and arrays to be encoded into the URL-encoded format, allowing for a JSON-like experience with URL-encoded. properties persist throughout the life of the application, in contrast with res.locals properties that are valid only for the lifetime of the request.You can access local variables in templates rendered within the application.
Some template engines do not follow this convention.
When specified, the IP addresses or the subnets are excluded from the address determination process, and the untrusted IP address nearest to the application server is determined as the client’s IP address.
NOTE: These settings apply only to dynamic files, not static files. You can use this mechanism to impose pre-conditions on a route, then pass control to subsequent routes if there is no reason to proceed with the current route.
When enabled, Express attempts to determine the IP address of the client connected through the front-facing proxy, or series of proxies.
The `req.ips` property, then contains an array of IP addresses the client is connected through.