In The Catcher in the Rye, the following five literary devices are prevalent in Holden's narration. In sum, they contribute to the humor and alienation in his voice and comment on the disillusionment of his episodic misadventure in post-war America:
A. Anaphora: (repetition at beginning of sentence) : “It rained on his lousy tombstone, and it rained on the grass on his stomach.”
B. Metaphor: “Or you’d just passed by one of those puddles in the street with gasoline rainbows in them.”
C. Alliteration: “crazy cannon”; “we can smoke till they start screaming at us.”
D. Verbal Irony (sarcasm, understatement, overstatement): "It’s really ironical, because I’m six foot two and a half and I have gray hair.”
E. Hyperbole: “The one side of my head—the right side—is full of millions of gray hairs.”
P.S. Actually, hyperbole is an example of verbal irony, as it is overstatement, but I think it still counts...
Salinger utilises a variety of literary devices to captivate and intrigue his audience, narrative style, colloquial language, anecdote, imagery and metaphor. There are many others.
We first encounter Holden as an unreliable first person narrator. Holden is vague, repetitive and ambiguous in his account of the events leading to his breakdown. He condemns his peers as 'phonies' and not worth his time, and yet is fascinated by their personal habits and motivations - as he shows with his descriptions of his teachers and peers.
Holden's use of colloquial language contributes to the ambiguity of his statements and assists in supporting the idea that Holden is not clear who he - or anybody else - really is.
We see Holden demonstrating his affection for his teacher, Mr Spencer, in the anecdote about his indian blanket in chapter 2. The imagery surrounding Holden's visit is particularly vivid.
When Dr Thurmer discusses Holden's expulsion he refers to the metaphor of life being a game. It is not a game at which Holden has any skill and he can see the irony in the last event for him at the school being the failed fencing contest - a result of Holden's ineptitude.