Use the change
event:
$( "#slider" ).slider({
value:0,
min: 0,
max: 2,
step: 1,
slide: function( event, ui ) {
$( "#amount" ).val( "$" + ui.value );
},
change: function( event, ui) {
if (ui.value == 0) {
$("#mindiv").show();
} else {
$("#mindiv").hide();
}
}
});