Question

I have one text box and button in asp.net like

<tr>
<td style="width: 100px">
 <asp:Label ID="lbltime" runat="server" Text="Enter Time"></asp:Label>
</td>
  <td style="width: 100px">
  <asp:TextBox ID="Txttime" onkeypress="return isNumberKey(event)" runat="server"></asp:TextBox>
</td>         
 </tr>
<tr>
  <td style="width: 100px" align="center">
  <asp:Button ID="Btntime" runat="server" Text="Button" />
  </td>
</tr>

Now I want to write JavaScript code to validate on my textbox which work when I click on button.
Now I want to know how to call function of JavaScript in button and
the function should do work like is
button should send the text box value to the function and function should check the value to integer number only. And if not found should give the error message in the dialog box that “please enter value in integer only”.

I’m trying the JavaScript like this:

function isNumberKey(textboxvalue)
      {
          evt=textboxvalue.text;
         var charCode = (evt.which) ? evt.which : event.keyCode
         if (charCode > 31 && (charCode < 48 || charCode > 57))
            textboxvalue.text="Enter in Integer Only";
            return false;

         return true;
      }

Answer 1

Use an <asp:CustomValidator /> for this.

<asp:CustomValidator id="CustomValidator1"
       ControlToValidate="myTextbox"
       ErrorMessage="Enter Integer only!"
       OnServerValidate="ServerValidation"
       OnClientValidate="isNumberKey"
       runat="server"/>

Your validation function looks like this:

function isNumberKey(oSrc, args) {
{
     evt=textboxvalue.text; 
     var charCode = (evt.which) ? evt.which : event.keyCode 
     if (charCode > 31 && (charCode < 48 || charCode > 57)) 
        args.isValid = false; 

     args.IsValid = true; 
}

If you just want to check the data type, you can use a CompareValidator:

<asp:CompareValidator id="CompareValidator1" 
         runat="server" ErrorMessage="Enter Integer only!" Operator="DataTypeCheck"
         ControlToValidate="Txttime" Type="Integer" />

The validators check on the client side if JavaScript is available AND on server side. All JavaScript will be generated for you.
On the server, you always have to check, whether your page is valid or not:

protected void OnButtonClick(object sender, EventArgs e)
{
  if (Page.IsValid)
  {
     ... // do your work on the server
  }
}