My rule of thumb is that if you apply math operators to it, then it should be a number, if not, make it a string. There are still rare cases where you use a nu

My rule of thumb is that if you apply math operators to it, then it should be a number, if not, make it a string. There are still rare cases where you use a number as an id because you're trying to save on space, but typically not for a web app. I've also found that there are even cases where you don't need record ids. Statistical data, for example.