I just found a difference. I'm making a mobile website, but I've mostly been testing on desktop Firefox. This works fine on Firefox:
var searchArray = searchValue.split(' '); // Split a string at the spaces.
BUT... it doesn't work on mobile Safari (iPhone 3GS running iOS 6.1). To make it work on mobile Safari, you have to use double quotes:
var searchArray = searchValue.split(" "); // Split a string at the spaces.
If you don't use double quotes, it doesn't split, it just puts the whole string into the first array element. That was a real puzzler for me and took quite a while to figure out; I dunno what even made me try switching the quotes, because I thought they were always supposed to act the same way. I haven't found anything on this problem by googling, so maybe this will help someone.