I have this java fern in a 30g tank that I got a few weeks ago and I was wondering if it is doing well or not because I saw that some of the leaves are turning brown and it started sprouting roots out of some of the leaves.
The roots are normal and the brown leaves aren't uncommon. Have you put it in the substrate though? You shouldn't do that; java fern need to sit on top of your gravel not in it.
Also rhe roots growinging from the leaves are baby plants. They will fall off on there own or you can pull them off gently before you can attaching them
the leaves are turning brown because these are the reproductive spores. In java ferns, the plantlets grow off the leaves. I also highly recommend tieing the java fern to some drift wood or rocks. You could also super glue it which is aquarium safe.