My mom always used a fork to grate pineapple for her jam. When I am time crunched, I peel the fruit, cut in big chunks and use the food processor to crush.
I used fresh pineapple. Canned crushed pineapple works just fine for this jam and saves a lot of time.
Adjust sugar according to your taste and the sweetness of the pineapple used.
Jam stays well in refrigerator for 4+ months.