How to change zoom size in Google map using JavaScript in ASP.Net

hi,

i have used this snippet for goole map multiple marker with database which workks FINE.

Problem, location in my database is so cloer to each other so the map has jumble up all the location with markers very closely is there any way to show the closed locations in an organize way

check the jumble up screen shot https://snag.gy/ycS13D.jpg