The salt could be created from the username (possibly with a standardize form step for case insensitively and maybe also including a site salt). On mobile devi

The salt could be created from the username (possibly with a standardize form step for case insensitively and maybe also including a site salt). On mobile devices client side hashing could affect battery life. If done with javascript, then login won't work without javascript enabled. Also, a work factor that doesn't slow down the slowest devices that a user might use could provide much less protection than desired, although the server could also do some work.