<select id="e1" multiple="multiple" style="width:300px">
<option value="AL">Alabama</option>
<option value="WY">Wyoming</option>
</select>
$("#e1").select2({
formatSelection:function(state){
return "<input type=\"text\" value=\""+1+"\" class=\"quantity\"/>" + state.text;
},
});
Example: http://jsfiddle.net/Gm668/