In the city of Los Angeles (which includes a lot of mini cities - Woodland Hills, Van Nuys, Beverly Hills, etc), they dont allow you to purchase any fireworks. You need to go out cities like El Monte, or Rosemead, etc to buy fireworks. But the frown on you using them here., for obvious reasons (fire, injuries, idiots).
Many of us go to various parks or venues (which are free), which usually have a 15 minute fireworks display starting at 9pm Wednesday night, and usually some music, bands or other entertainment beforehand.