Hold the "a" key, the space key, and the right arrow key, then click onto another page or tab. If you then click back on this page, the spaceship will be auto-spinning and shooting. It is still possible to die (I have), but it is improbable to die.
Much thanks to mrbrown1007 for the original project. If you follow the instructions, the project will auto-shoot, but it is still possible to die. Have fun!