Lets say you have a web form with one more serverside controls like one below,
1<asp:TextBox ID="txtEmail" runat="server" class="txtBoxLarge textSmall" placeholder="Enter Email Address"></asp:TextBox>23<asp:RequiredFieldValidator ID="rfvEmail" runat="server" ErrorMessage="Enter Email" Display="None" ControlToValidate="txtEmail" ValidationGroup="groupName"></asp:RequiredFieldValidator>
And you need to do some client side operations along with client side validation, the button triggering the whole operation will be like,
1<asp:Button ID="btnSubmit" CssClass="blueBtnLarge" runat="server" Text="Continue" ValidationGroup="groupName" OnClick="btnSubmit_Click" OnClientClick="ClientSideClick(this)" UseSubmitBehavior="False" />
Here OnClick will send request to server side and OnClientClick will execute on client side before control passed to server. OnClick only will be triggered if OnClientClick returned true.
And the client side JavaScript function we call on OnClientClick will be like below,
1<script type="text/javascript">2 function ClientSideClick(myButton) {3 // Any operation before validation goes here45 // Client side validation6 if (typeof (window.Page_ClientValidate) == 'function') {7 if (window.Page_ClientValidate('groupName') === false) {8 document.getElementById('someDivElementWithErrorExplanation').style.display = 'block'; // Showing error on validation, modify to your needs9 return false;10 }11 }12 document.getElementById('someDivElementWithErrorExplanation').style.display = 'none';1314 // Any operation after client side validation passess goes here.1516 return true;17 }18</script>
That’s it. Also, don’t forget to notice the usage of the ValidationGroup all over the code above.