Knocout Js在自定义绑定

Question

我正在使用knockout js自定义绑定，并且我生成自动索引值以生成其工作正常的唯一ID，但我需要在我的自定义绑定中获取该ID值，如何实现此功能我无法做到这一点需要帮助

 //this div is inside the for each loop
 before page load
<div data-bind="myFavouriteItem:({Favitem:someitem}),attr: { id: 'Fav_' + $index() }" class="fav"></div>

 after page load get data and ID is generated dynamically
<div data-bind="myFavouriteItem:({Favitem:someitem}),attr: { id: 'Fav_' + $index() }" class="fav"  id="Fav_0"></div>

//custom Binding handler
ko.bindingHandlers.myFavouriteItem= {
    update: function (element, valueAccessor) {
       //inside the consloe.log(element) i am getting above div with ID "Fav_0"
       //here i need to get  the attr ID value 

}