Data binding using knockoutjs

I want to display data to a table using datatable knockoutjs binding. I am using the below link and code to render the data into a table. http://datatables.net/dev/knockout/

The only change I made in the above example is the rendering of the age data. I added an age col input field for any record and an Updatebutton at the bottom of the table so that the user can change their age and click on the update button. updated automatically and on the next page it should reflect in the table.

The problem is that I cannot update the local js model "people" and hence could not bind the updated data with knockoutjs.

ko.observableArray.fn.subscribeArrayChanged = function(addCallback, deleteCallback) {
    var previousValue = undefined;
    this.subscribe(function(_previousValue) {
        previousValue = _previousValue.slice(0);
    }, undefined, 'beforeChange');
    this.subscribe(function(latestValue) {
        var editScript = ko.utils.compareArrays(previousValue, latestValue);
        for (var i = 0, j = editScript.length; i < j; i++) {
            switch (editScript[i].status) {
                case "retained":
                    break;
                case "deleted":
                    if (deleteCallback)
                        deleteCallback(editScript[i].value);
                    break;
                case "added":
                    if (addCallback)
                        addCallback(editScript[i].value);
                    break;
            }
        }
        previousValue = undefined;
    });
};`


 `var data = [
    { id: 0, first: "Allan", last: "Jardine", age: 86 },
    { id: 1, first: "Bob", last: "Smith", age: 54 },
    { id: 2, first: "Jimmy", last: "Jones", age: 32 }
]; `

   `var Person = function(data, dt) {
    this.id    = data.id;
    this.first = ko.observable(data.first);
    this.last  = ko.observable(data.last);
    this.age   = ko.observable(data.age);

    // Subscribe a listener to the observable properties for the table
    // and invalidate the DataTables row when they change so it will redraw
     var that = this;
    $.each( [ 'first', 'last', 'age' ], function (i, prop) {
        that[ prop ].subscribe( function (val) {
            // Find the row in the DataTable and invalidate it, which will
            // cause DataTables to re-read the data
            var rowIdx = dt.column( 0 ).data().indexOf( that.id );
            dt.row( rowIdx ).invalidate();
        } );
    } ); 
};

    $(document).ready(function() {

var people = ko.mapping.fromJS( [] );
    //loadData();

    var dt = $('#example').DataTable( {
        "bPaginate": false,
        "bInfo" : false,
        "bAutoWidth" : false,
        "sDom" : 't',
        "columns": [
            { "data": 'id' },
            { "data": 'first' },
            { "data": 'age',
                "mRender": function (data, type, row ) {    
                                var html = '<div style="display:inline-flex">' + 
                                                '<input type="text" class="headerStyle h5Style" id="ageId" value="'+data()+'"/>' +
                                                '</div>';

                                  return html;
                            } 
             }
        ]


    } );


    // Update the table when the `people` array has items added or removed
    people.subscribeArrayChanged(
        function ( addedItem ) {
            dt.row.add( addedItem ).draw();
        },
        function ( deletedItem ) {
            var rowIdx = dt.column( 0 ).data().indexOf( deletedItem.id );
            dt.row( rowIdx ).remove().draw();
        }
    );

    // Convert the data set into observable objects, and will also add the
    // initial data to the table
    ko.mapping.fromJS(
        data,
        {
            key: function(data) {
            var d = data;

                return ko.utils.unwrapObservable(d.id);        
            },
            create: function(options) {
                return new Person(options.data, dt);
            }    
        },
        people
    );



} );