It's time to bring on a composer for Justice League and according to the The Hollywood Reporter that composer is Danny Elfman.
They have brought on Elfman just as the reshoots that Joss Whedon is doing have started. Zack Snyder had to step away from the project for a family tragedy so Whedon was brought on. Snyder was previously working with Antonius Holkenborg, aka Junkie XL, but he had to move onto scoring the upcoming Tomb Raider reboot.
Elfman has worked with Whedon before in a very similar situation. Elfman was brought on rather late in the game to Whedon's own Avengers: Age of Ultron to add to music already written by Brian Tyler
Summary: Fueled by his restored faith in humanity and inspired by Superman's selfless act, Bruce Wayne enlists the help of his newfound ally, Diana Prince, to face an even greater enemy.
Justice League will be directed by Zack Snyder and stars Ben Affleck, Gal Gadot, Jason Momoa, Ezra Miller, Ray Fisher. and Henry Cavill. It will be released on November 17, 2017.