Except that there are plenty of cross-browser-incompatible features that aren't exactly "bleeding-edge", unfortunately. For example, in IE < 9, there is no imp

Except that there are plenty of cross-browser-incompatible features that aren't exactly "bleeding-edge", unfortunately. For example, in IE < 9, there is no implementation of "Array#indexOf" -- the only way to check if a value is present in an array is to write out a loop to check each element.