"Onion John" is as different from most children's books as Onion John is different from the man next door. Instead of cardboard-thin characters cut to fit the plot, the story grows out of the actions and reactions of people too real to be forgotten when the book is closed. Packed with humor, odd information (why witches ride broomsticks), descriptions that never burden the action, and warmth, it will appeal to the more sensitive 10-14's. And to most adults. (p. 5B)