Summarize this article:

Pineapples do not need to be refrigerated for the first few days you have them at home.  In fact, if you intend to eat your pineapple within a day or two of purchasing it, feel free to just store it on your counter.  Keep an eye on your pineapple to make sure it doesn’t begin to exhibit signs of deterioration as it sits. It is recommended that you purchase your pineapple on the same day you intend to eat it so as to avoid deterioration. If you would like to prolong the life of your pineapple for a few more days, you can keep it in your refrigerator.  Remember, pineapples do not have a significant shelf life even when refrigerated so it is recommended that you eat your pineapple within 3-5 days even when using this method.  Wrap the pineapple in plastic before placing it in the refrigerator. Check the pineapple each day for signs of deterioration. You can prolong the life of your pineapple by another day or two beyond simply refrigerating it by slicing it first.  It can be more difficult to know if your pineapple has begun to deteriorate once it is sliced, so it is recommended that you eat the pineapple within 6 days of purchase even using this method.  Use a serrated knife to cut off the top of the pineapple off, then slice off each of the sides. Once you have the outer portion of the pineapple removed, slice it to a thickness of your liking, then use a cookie cutter or knife to remove the core from the center of the slices. Store your pineapple slices in an airtight container like Tupperware to maximize its lifespan.

Summary:
Store the pineapple on your counter. Refrigerate your pineapple whole. Refrigerate sliced pineapple.