However, as it turns out, Todd Phillips may have been misquoted. In an interview with ComicBook.com, Phillips cleared the air, saying that the film isn’t based on ONE particular comic book storyline, but many different ones.

In the same interview, Phillips explained that the main reason he decided to set the film in the late 70s and 80s is to keep it as far away from the DCEU (the universe in which Batman V Superman, Aquaman, etc is set in) as possible. Official synopsis of Joker:  Director Todd Phillips Joker centres around the iconic arch nemesis and is an original, standalone fictional story not seen before on the big screen. Phillips’ exploration of Arthur Fleck, who is indelibly portrayed by Joaquin Phoenix, is of a man struggling to find his way in Gotham’s fractured society. A clown-for-hire by day, he aspires to be a stand-up comic at night…but finds the joke always seems to be on him. Caught in a cyclical existence between apathy and cruelty, Arthur makes one bad decision that brings about a chain reaction of escalating events in this gritty character study. Joker is set to hit Malaysian cinemas on 3 October 2019.

Joker Director Clears Up Earlier Comments  Film Is Actually Based on the Comics - 56