slider and image opacity

http://stackoverflow.com/questions/13305456/how-to-apply-css-rules-to-html-element-using-extjs

HTML

<link rel="stylesheet" href="http://cdn.sencha.io/ext-4.1.0-gpl/resources/css/ext-all.css">
<img id="my-img" src="http://www.howtobuildahouseblog.com/wp-content/uploads/2018/07/modern-bedroom-2.jpg" />

JavaScript

var slider = Ext.create('Ext.slider.Single', {
    width: 200,
    value: 100,
    increment: 2,
    minValue: 0,
    maxValue: 100,
    renderTo: Ext.getBody()
});

slider.on('change', function(sl, val) {
    Ext.fly('my-img').setOpacity(val/100);
});