how to validate at client side

mohdazeemuddin ahmed

17y3.3k.NET

Hi to all master of asp.net and c#
how to do the client side validation using c# and with out using required field validation control i wrote the code of javascript in head tab and i write in page_load method
protected void Page_Load(object sender, EventArgs e)
    {
        btnAdd.Attributes.Add("onclick", "return validate()");
    }
but its not checking the fields and javascript is

where i am doing mistake i don't know

5 Replies

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Niradhip Chakraborty17y ago
You can always use custom validation. Hackers can disavle the browser scripting and bypass the validation in javascript.
mohdazeemuddin ahmed17y ago
Thanks for your support

to do validation which is good JavaScript or custom Validation. i don't want do post back if there is any missing field available.
Kirtan Patel17y ago
Why don't you use Custom Validator Control its Easy to use then Using that Alert like Warning message

and Even you dont need to use getElementById to Locate Control :)

use it like below code

aspx Code
```
 <asp:TextBox ID="txtPrimeNumber" runat="server">asp:TextBox>

 <asp:CustomValidator ID="CustomValidator1" runat="server"ErrorMessage="Invalid Prim Number" 
  ClientValidationFunction="CheckPrime" ControlToValidate="txtPrimeNumber" Display="Dynamic">
asp:CustomValidator>
```
```
Validation Script in aspx File 
```
```
<script language="JavaScript">

  function CheckPrime(sender, args)
  {
    var iPrime = parseInt(args.Value);
    var iSqrt = parseInt(Math.sqrt(iPrime));

    for (var iLoop=2; iLoop<=iSqrt; iLoop++)
      if (iPrime % iLoop == 0) 
      {
         args.IsValid = false;
         return;
      }

    args.IsValid = true;
  }

script>

Dont Forget to mark "Do you like answer" it will give some credits to me :)
```
Master Billa17y ago
Hi

When you are write javscript, you keep in mind its JAVA. so you need take all attribute also here.

So here i have corrected your code. try this

protected void Page_Load(object sender, EventArgs e)
    {
        btnAdd.Attributes.Add("onclick", "return validate();");
    }
but its not checking the fields and javascript is

Thank you
Niradhip Chakraborty17y ago
Javascript is case sensative. Your function Validate() 'V' is caps but when you are calling it in pagebehind you have written validate() 'v' is small. Please use ither in caps or in small in both the places.