One solution is to toggle the concatenatation of the js by editing wp-config:
require_once add below code into file :
That MAY not work though depending on what is combining the js into one (order of operations has to be considered).
If you use Cloudflare, check that Rocket Loader is not enabled. If it is, this is the culprit. Disable Rocket Loader, wait ~5 minutes and everything should be back to normal. You may need to clear cache also.