Option for static resources ?

I am guessing that sprites and new instances of objects are created on the fly with the new operator

or malloc or something similar.

Is it possible to have say an array of 1,000 bullet sprites pre-allocated and just use those without creating them with memory allocation?

Then those bullet sprites could just be re-circulated.

Another example would be that you know your game doesn't ever have more than 100 monsters on the screen.

Like in c++ you just said "Monster array[100] ;" so you have pre-allocated objects

without having to use dynamic memory allocation?

Browser vendors actually advise to avoid pre-allocation because it can decrease performance. Apparently it impacts the escape analysis optimisations that help speed up garbage collection.