How does the author use foreshadowing in The World According to Garp?

Irving uses foreshadowing, a literary device that creates expectation or sets up an explanation of later developments, to great effect in The World According to Garp. One example is Garp's childhood confrontation with Bonkers the dog. The vicious Newfoundland bites off a piece of Garp's ear. This scene foreshadows Garp's retaliation when, as a teenager, Garp bites off a piece of the dog's ear. Another instance of foreshadowing involves the broken knob on the gearshift of the Garp family's Volvo. The Garps procrastinate replacing the knob, and Duncan ultimately loses an eye when his head is impaled on the knobless shifter in a car accident.