Knockout set view-model field value

Question

Model has a field, TotalCount . On button click, how I could change its value?

    <input id="Qty" type="text" style="width:25px;" 
     value="@Model.TotalCount" />

    var pageKoModel;
    var pageKoModelData = @Html.Raw(Json.Encode(Model));
    $(document).ready(function () {
        pageKoModel = new Object();
        ko.mapping.fromJS(pageKoModelData, {}, pageKoModel);
        ko.applyBindings(pageKoModel);
    });

Answer 1

data-bind is not present in the code. So, try replacing the input field with this code

<input id="Qty" type="text" style="width:25px;" data-bind="
value:TotalCount" />

if, still it does not work then,try with

<input id="Qty" type="text" style="width:25px;" data-bind="
value:pageKoModel.TotalCount" />

Answer 2

this works for me like:

<input tabindex="1" type="text" data-bind="value: $root.TotalCount" maxlength="5" 
onkeypress="return onlyNumberKey(event);" style="width:35px;" />