js is dynamically compiled, also known as runtime compilation. The js engine re-optimizes and compiles the code, which is then processed by the interpreter.

estimate means that the js engine optimizes the code according to a certain policy when loading, and then interprets and executes it.
there is an escape process for writing files other than your own js, such as jsx.

first of all, just because you don't have to compile manually doesn't mean you don't compile. How can you execute the program without editing the computer?
js is dynamically compiled, that is, when the program loads the js code, it is automatically edited and then executed by the computer.
so js will still be compiled, so precompilation is normal