jQuery Forum

You're checking the current value of the slider inside the slide callback, but it hasn't been updated yet. This is because the slide callback is cancelable (by return false). For this to be effective, you need to be able to get both the current and the potential new values. Right now you're getting the current (or previous) value by $(this).slider('value') but what it looks like you want is the new (or potential) value by ui.value. So change

1. slide: function () {
2.     var val = $(this).slider('value');

to

1. slide: function (event, ui) {
2.     var val = ui.value;