Question

is there any default way in kendo DatePicker for ensuring (and alerting user accordingly) that To date is always greater than or equal to From date.

Answer 1

There is no default way but there is one example in Kendo UI demos page that might help you. Read here

Basically given this HTML:

<div class="demo-section" style="width:470px">
    <label for="start">Start date:</label>
    <input id="start" value="10/10/2011"/>

    <label for="end" style="margin-left:3em">End date:</label>
    <input id="end" value="10/10/2012"/>
</div>

And this DatePicker initialization:

var start = $("#start").kendoDatePicker({
    change: startChange
}).data("kendoDatePicker");

var end = $("#end").kendoDatePicker({
    change: endChange
}).data("kendoDatePicker");

start.max(end.value());
end.min(start.value());

They suggest the following startChange and endChange functions:

function startChange() {
    var startDate = start.value();

    if (startDate) {
        startDate = new Date(startDate);
        startDate.setDate(startDate.getDate() + 1);
        end.min(startDate);
    }
}

function endChange() {
    var endDate = end.value();

    if (endDate) {
        endDate = new Date(endDate);
        endDate.setDate(endDate.getDate() - 1);
        start.max(endDate);
    }
}