Monitor network request URL and response content (Throw custom exceptions) - ajax

Question

How can network requests be monitored and evaluated for their request URL, parameters, request, and response data?
Desired solution
I want to be notified or being given a custom exception, if specific content occurs in request or response.
Example
Assume a web application with many dynamic Ajax requests. A request or response might contain a broken value, e.g. undefined.
Request URL:
http://localhost:8080/app/?undefined=1
Response JSON data:
{"undefined":"1"}
Attempts
Filtering for request content in Dev Tools is not possible
PostMan tests seem not viable (e.g. no user interactions)
Not tried/found yet
Guesses of what might work ...
Software to intercepts requests and log/alert details
Proxying any URLs on an OS via some standalone application

Answer 1

If importing axios, you could leverage custom interceptors:
// Add a response interceptor
axios.interceptors.response.use(function (response) {
// Any status code that lie within the range of 2xx cause this function to trigger
// Do something with response data
return response;
}, function (error) {
// Any status codes that falls outside the range of 2xx cause this function to trigger
// Do something with response error
return Promise.reject(error);
});
// Similar functionality can be achieved for request
axios.interceptors.request.use(function (config) {
// Do something before request is sent
return config;
}, function (error) {
// Do something with request error
return Promise.reject(error);
});

Answer 2

Proxy software
For this case, any proxy that comes with logging ability, or can be extended:
https://mitmproxy.org
https://github.com/http-party/node-http-proxy
Exemplary for many variants under NodeJS
Tunneling
Expose localhost to a domain for testing:
https://ngrok.com
Use the logging capability to get request details:
https://ngrok.com/docs/ngrok-agent/api#list-requests
Localhost vs. 127.0.0.1
localhost should better become 127.0.0.1 or a custom dev domain. On MacOS, localhost did not work with HTTP interceptor browser plugins.