In custom text facet I want to check value of previous row's cell.
I tried rows[row.index - 1]
with no result.
google refine does not allow you to get the previous row directly. You may wants to have a look at the fill down option but not sure it will help with your project: http://googlerefine.blogspot.ca/2012/03/fill-down-right-and-secure-way.html