FFI function pointers come in two flavours: Foreign functions and callbacks. Function pointers are always represented as pointer objects (or null for null pointer, ie. "no function"). It is not possible to use a TypedArray as a function pointer, meaning that its not possible to write your own assembly into a buffer and use it as an executable function.

A foreign function pointer can be called as a function using Deno.UnsafeFnPointer.

Callback function pointers can be created using Deno.UnsafeCallback. The resulting UnsafeCallback instance contains a pointer member that can be passed to FFI symbol calls as a pointer value ("function" type parameter, or "pointer").

Fast API support

Function pointers are equivalent to pointers on the Fast API front. Starting with Deno 1.31.0 they're always Fast API compliant. See Pointers for details.