jQuery UI Slider (setting programmatically)

It depends on if you want to change the sliders in the current range or change the range of the sliders.

If it is the values in the current range you want to change, then the .slider() method is the one you should use, but the syntax is a bit different than you used:

$("#slider").slider('value',50);

or if you have a slider with two handles it would be:

$("#slider").slider('values',0,50); // sets first handle (index 0) to 50
$("#slider").slider('values',1,80); // sets second handle (index 1) to 80

If it is the range you want to change it would be:

$("#slider").slider('option',{min: 0, max: 500});