What is the author's style in Rumble Fish by S. E. Hinton?

The book is written in a tough, breezy style, as Rusty James would speak but without any curse words. It seems unbelievable that the characters in the book would not curse, but obviously Hinton could not depict their talk realistically and have the book published for a young-adult audience. Instead, she implies cursing, as when Rusty James says, "I said something to her I wouldn't normally say to a chick, but she really got on my nerves. She didn't flinch."