CAT AND HAIRBALL???????????????

So my cat has done this a few times. She would suddenly sit there and start to cough up something. At first, i thought she she was having an asthma attack!!! Anyways, i found out that she was actually trying to cough out a hairball. But the thing is that everytime she is coughing, nothing would come out. That's when i thought she was having an asthma attack. If a hairball came out, i knew it wasen't an asthma attack. When she is coughing, i would always hear her swallowing it back in. It was like she was trying to barf but then she just swallowed it. IS SHE OK??