Very few systems in the real world implement OAEP, and even with OAEP you have to watch out for Manger's padding oracle attack (susceptibility to which may be commented out of the Javascript RSA you've posted here --- I'm like 50/50 on this because I've never taken the time to implement Manger because I've never been professionally asked to look at an OAEP implementation because, again, OAEP is pretty rare --- at this point, if you're designing a modern system, you're not using RSA.)