Can i use for in loop for arrays?

Yes.
It is possible to use for-in loop  for arrays,
BUT

• it can cause some dodgy  logical errors 
• order of listening the properties can be a little bit random (It's not quaranteed) 

 So it is highly NOT RECOMMENDED to use for in for arrays.

Just remember:
use   for loops with arrays and for-in loops for objects .


Source: Stoyan Stefanov - JavaScript Patterns  - O'Reilly(2010)