It has long been suspected that he had written for decades at his isolated home in New Hampshire, despite publishing nothing since 1965.
The four other titles to be published between 2015 and 2020 are: A Counterintelligence Agent's Diary about his time interrogating prisoners of war; A World War II Love Story, based on his brief marriage to Sylvia, a suspected Nazi; A Religious Manual detailing his adherence to Advaita Vedanta Hinduism later in life; and The Complete Chronicle of the Glass Family, five stories about Seymour Glass, a recurring character in other works.
The documentary traces Salinger's childhood and throws fresh light on his romantic history, including a relationship with Oona O'Neill, daughter of playwright Eugene. She dumped Salinger for Charlie Chaplin after he went to World War II.
Rejection appeared to drive his writing as he started The Catcher in the Rye and, say some reports, carried six chapters of the unfinished book during the D-Day operations. The book would make his name and endear him to generations of readers.
But the war also left him with what would now be diagnosed as post-traumatic stress disorder (PTSD).
"I dig my foxholes down to a cowardly depth," he wrote in a letter to a friend. Salerno, a Hollywood scriptwriter who spent a decade and US$2 million ($2.5 million) of his own money on the project, interviewed hundreds of people and amassed piles of documents, letters and photographs.
A fellow soldier provided a wartime snapshot of a moustached Salinger looking up from a notebook. It is the only known photo of him working on The Catcher in the Rye, according to Salerno, who has been working on a sequel to Avatar in his "day job".
Speaking after the screening, he said: "Having people speak for the first time was a huge challenge ... doors just slammed in your face for the first couple of years, but I was very grateful to finally have people come forward and share their stories.
"World War II really was the transformative trauma of J.D. Salinger's life," he added. "It made him as an artist, but it broke him as a man. He was living with PTSD throughout his life."
In keeping with the author's obsessive wish for secrecy, his family and publishers have made no statement on the contents of the documentary and accompanying 700-page book.
Movie preview
What: The documentary Salinger about the reclusive American author of Catcher in the Rye
Where and when: At selected cinemas from tomorrow
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