I'm using a jquery knob plugin. I want to make the knob readonly on button click.

```
(function() {
$(".dial").knob({
    'min':0,
    'max':360,
    'change' : function(degree){
        var img = $(".volume_bttn");
        if(radioSwitchState == 1)
        {
            img.css('-moz-transform', 'rotate('+degree+'deg)');
            img.css('-webkit-transform', 'rotate('+degree+'deg)');
            img.css('-o-transform', 'rotate('+degree+'deg)');
            img.css('-ms-transform', 'rotate('+degree+'deg)');
            var vol = ((degree)/360).toFixed(2);
            //console.log(vol);
            $("#jquery_jplayer_1").jPlayer("volume",(360-vol));
        }
    },
    'fgColor' : '#460E09',//460E09
    'bgColor' : "transparent",//transparent
    'width' : 107,
    'thickness' : 0.3,
    'displayInput' : false,
    'linecap' : 'butt'
    });
});

```

This is a code where I'm initializing the knob. How to make it readonly on button click?(I repeat)