Using Angular 9 Application written using Typescript, there the HTML Content is not visible, and due to this not able to test
- JMeter is backend-agnostic, it doesn't care what is the underlying technology used in the system under test.
- Properly configured HTTP(S) Test Script Recorder is capable of recording HTTP and/or HTTPS requests which should be sufficient for testing your application because browsers mainly send HTTP requests and render the responses
If your application looks/behaves differently when you're accessing it using JMeter as a proxy the reasons might be in:
- You didn't import JMeter's self-signed certificate into your browser (or the certificate has expired), see HTTPS recording and certificates chapter of HTTP(S) Test Script Recorder documentation for more details, double check your configuration when it comes to proxy and certificate settings
- You accessed the application previously and it is partly or fully blocked by HSTS, in this case clear your browsing history at least for the domain you're testing
Also be aware of alternative way of recording a JMeter test: JMeter Chrome Extension. In this case you won't have to worry about proxies and certificates and due to "non-invasive" nature of the extension you shouldn't experience any problems with browsing experience.