Question

In a textbox user can enter date. In OnChange event I am trying to validate the date using javascript, if it is not a valid date showing an alert message and setting the focus on the textbox.

Here when I enter invalid date and press tab, the onchange events fires , in case of invalid date it does not set focus on the texbox, instead the focus is set on next textbox in the form.

<asp:TextBox ID="txtDateOfBirth" runat="server"
    onchange="validateDate(this)"></asp:TextBox>

function validateDate(sender) {
    if (!Date.parseInvariant(sender.value, "MM/dd/yyyy")) {
        alert("date is incorrect");
        sender.focus();
    }
}

Answer 1

Try using onblur instead of onchange:

<script type="text/javascript">
    check = function (sender) {
        if (sender) {
            alert("check");             
            sender.focus();
        }
    }
</script>
<asp:TextBox ID="txtTest" runat="server" onblur="check(this);"></asp:TextBox>

In the above example, focus is returned to the input as expected.