Илья

<div id="slider"></div>
<div id="value"></div>

const min = 100;
const max = 500;

$('#slider').slider({
  min,
  max,
  value: min + Math.random() * (max - min) | 0,
  range: 'min',
  animate: 'fast',
  slide: (e, ui) => $('#value').html(max - ui.value + min),
});