For those you want to use the natives functions here's a file that will help you.
Link : https://github.com/Mcfloy/natives
To use it simply add it on your folder and type :
const NATIVES = require('folder/natives');
Only JS for now, I'll probably do a TS one based on the work of CocaColaBear or Pet-Platoon.
(A little example to show you how to get infinite ammo)
var weaponHash = NATIVES.WEAPON.GET_SELECTED_PED_WEAPON(player.handle);
mp.game.graphics.notify(`Result: ${weaponHash}`);
NATIVES.WEAPON.SET_PED_INFINITE_AMMO(player.handle, true, weaponHash);