on impulse
Done with recklessly or impulsively, without due thought or consideration. I had always wanted a classic muscle car, so after getting the payout from my insurers I decided to buy one on impulse. I understand that you're dissatisfied with your job, but don't just quit it on impulse—have a plan in place first for what you're going to do next.
on impulse
after having had an impulse or sudden thought. On impulse, Bob decided to buy a car. I didn't need a cellular telephone. I just bought it on impulse.