What is JIT compilation in Angular ?

JIT compilation as the name implies, compiles the application Just-in-Time in the browser at runtime. The application code along with the angular compiler is downloaded by the browser. At run-time, when a request is issued to the application, the JIT-compiler in the browser compiles the application code to executable code. The user needs to wait for the application to compile first when the request is placed. 

By default,  development build is JIT compiled. Below two commands use JIT compilation as default is JIT.

ng build
ng serve