Try
$("#slider").dateRangeSlider({
range: {min: new Date(2012, 0, 1)}, //use minimum range
bounds: {
min: new Date(2012, 0, 1),
max: new Date(2012, 11, 31, 12, 59, 59)
},
defaultValues: {
min: new Date(2012, 1, 10),
max: new Date(2012, 4, 22)
}
});