odd & even methods improvements

[dsonet]

I notice here use % to test if the number is even or odd. I suggest we use bitwise operator here to get the best performance. So, we can rewrite them as:

even: function(elem, i){

return !( i & 1 );

}, odd: function(elem, i){

return ( i & 1 ) === 1;!!(i & 1)

},

[snover]

There is no effective performance difference between these two operations.  jsperf test