Loop through Kendo Grid Column values - JavaScript

Question

What is correct way to loop through Kendo Grid Column Values in JavaScript and perform an if statement on the values:

    var dataSource = $("#grid").data("kendoGrid").dataSource;
    // Gets the full set of data from the data source
    var allData = dataSource.data();
    dataSource.fetch();
    var datasourcedata = dataSource.data();

    var dataitem = datasourcedata[i].(columnName);
    for (var i = 0; i < dataitem.value; i++) {
        if (dataitem.value == 0) {
            alert("error message");
          e.preventDefault();
            return false;
        }
    }

   });

Answer 1

$.each(kendoDataSource.schema.model.fields, function (propertyName, propertyValue) {
    alert(filter.field);
});