Even experienced riders on expensive bikes occasionally "drop a chain". In the right context, and with enough momentum and presence of mind, one can often move the front shifter around and spin the pedals like mad, and some teeth will grab the chain and pick it back up, without ever even stopping!

But of course, if you don't feel comfortable trying this, by all means attempt to safely stop! Don't risk your life trying this for the first time in traffic! You can often do the same thing if you move the shifter such that the front derailleur pushes the chain towards the center (i.e. different directions depending on whether the chain dropped to the inside or outside), then get the rear wheel off the ground by lifting the seat with one hand, then turn the pedals either with the other hand, or pushing with one foot; often you can achieve the same thing. But if that fails, you can pretty much always get it back on with your hands, although you gotta try to wipe your hands of on some grass or something. This is one reason many bkers carry latex gloves.