How does the author use foreshadowing in Jeffty Is Five?

The narrator foreshadows Jeffty's death before it actually occurs. After Donald ushers the boy out of the electronics store, he hears a terrible sound in the distance. He assumes that it is coming from one of the television sets on display, but he can't decide which one. Interestingly, the chain of events that leads to Jeffty's demise suggests that television killed Jeffty, and when Donald later attempts to find the radio stations of the past he can never do so. There is a symbolic connection, which implies that television killed radio.