var countMost = function(str){
if(!str) return;
var _count = 0, _temp = 0, _reg, _char;
for(var i=0; i<; i++){
_reg = new RegExp((i), 'g');
_temp = (_reg).length;
if(_temp > _count){
_count = _temp;
_char = (i);
}
}
return _count;
//return {count:_count, char:_char};
};