Using setAt function in listview

Question

I am not sure how to use the setAt funvtion in listview - should it be used on the listview object or the binding object? Here is my question

DataExample.js file

 var dataArray = new Array();
 var dataList = new WinJS.Binding.List(dataArray);
// Create a namespace to make the data publicly
// accessible. 
    var publicMembers =
        {
            itemList: dataList,
            data_array: dataArray

        };
    WinJS.Namespace.define("DataExample", publicMembers);

I use the splice method to add values to the listview like this. It has 2 sub values - "data" and "noteindex"

 DataExample.itemList.splice(0, 0, { data: "Start noting", noteindex: DataExample.itemList.length });

At some point I'd like to access the values stored in the list view and update them. I am not sure what to do here. I am using the below code but it is not working

var newData = "Hello"
var newnoteIndex = "2"

DataExample.itemList.setAt[j].data.data = newData;
DataExample.itemList.setAt[j].data.noteindex = newnoteIndex;

How do I update the values written in the list?