css - JavaScript - Getting Value from switch

I've made a "switch" UI element using CSS that I really
like. It's intended to be used for on/off scenarios. Basically, a fancy checkbox. My
switch is defined in html like
this:

html

            class="switch">            id="switchText>Off
            type="text/javascript">
 $('.switch > checkbox').on('change',
            function(e) {
 alert('here');
 var isChecked = // what goes
            here?
 if (isChecked) {
 alert('turned on');
 } else
            {
 alert('turned off');
 }

            });

My
css for this component looks like
this:

css

.switch
            {
 cursor:pointer;
 display:inline-block; 
 margin:1px
            0;
 position:relative;

            vertical-align:middle
}

.switch input {

            filter:alpha(opacity=0);
 opacity:0;

            position:absolute;
}

.switch span {

            background-color:#c9c9c9; 
 border-radius:12px;
 border:1px solid
            #eee; 
 display:inline-block; 
 position:relative;

            height:24px; 
 width:52px;
 -webkit-transition:background-color
            .33s;
 transition:background-color
            .33s
}

.switch span:after {

            background-color:#fff; 
 border:1px solid #ddd;
 border-radius:20%;
            
 bottom:1px;
 content:"";
 left:2px; 

            position:absolute;
 top:1px;
 width:24px;

            -webkit-box-shadow:1px 0 3px rgba(0,0,0,.05);
 box-shadow:1px 0 3px
            rgba(0,0,0,.05);
 -webkit-transition:all .13s ease-out;

            transition:all .13s ease-out
}

.switch
            input:checked+span:after {
 left:26px;
 border:none;

            -webkit-box-shadow:-2px 0 3px rgba(0,0,0,.1);
 box-shadow:-2px 0 3px
            rgba(0,0,0,.1)
}

.switch input:checked+span {

            background-color:#eee
}

.switch span{

            border-color:#818A91
}

.switch
            input:checked+span{

            background-color:#818A91
}

When
a user flips the switch, the onchange event gets fired. That
gives me access to the properties found href="http://www.w3schools.com/jsref/dom_obj_event.asp"
rel="nofollow">here. However, I do not see how I can determine if the
switch is on or off. In other words, how do I know if the checkbox is checked or not?
I'm trying to keep the implementation generic and not reference IDs because a page will
have multiple switches.

Thank you for any help
you can provide.