Validation message

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I have two textboxes and a button. I want to alert a validation message when first text box is empty. But it is not working. The code is written below.

function validation()
{
    var valfirst= document.getElementById("FirstName").value;
        if(valfirst == null || valfirst == "")
    {
        return false;
    }
    else
    {
       return(valfirst);
    }

}

<html>
  <body>
    <script type="text/javascript" src="External.js">
    </script>
    <form id="frm1" method="get">
      First Name: <input type="textbox" id="FirstName"/>
      Second Name:<input type="textbox" id="SecondName"/>
      <input type="button" value="Submit" onClick="validation()"/>
    </form>
</body>
</html>

Posted 12-Jan-11 18:59pm

Lyn123

Updated 12-Jan-11 19:01pm

JF2015

v2

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Al-Farooque Shubho · Answer 1 · 2011-01-12T19:20:00

Following is the corrected code:

XML

<html>
  <body>
    <script type="text/javascript">
        function validation() {
            var valfirst = document.getElementById("FirstName").value;
            if (valfirst == null || valfirst == "") {
                alert("FirstName is required");
                return false;
            }
            else {
                return true;
            }
        }
    </script>
    <form id="frm1" method="get">
      First Name: <input type="textbox" id="FirstName"/>
      Second Name:<input type="textbox" id="SecondName"/>
      <input type="submit" value="Submit" onClick="return validation()"/>
    </form>
</body>
</html>

However, I'd recommend to use the Asp.net Validators for validation. See http://quickstarts.asp.net/QuickStartv20/aspnet/doc/validation/default.aspx[^] to learn about this.

Kirankumar Ballapalli · Answer 2 · 2011-01-12T19:29:00

Hi,

Rewrite the javascript fucntion as follows.
fucntion Validate()
{

C#

var valfirst= document.getElementById("FirstName").value;
       if(valfirst == null || valfirst == "")
   {
       document.getElementById("FirstName").focus();
return false;
   }

C#

var vallast= document.getElementById("LastName").value;
       if(vallast== null || vallast== "")
   {
       document.getElementById("LastName").focus();
return false;
   }

}

Do the HTML page modifications as follows.

XML

<html>
  <body>
    <script type="text/javascript" src="External.js">
    </script>
    <form id="frm1" method="get">
      First Name: <input type="text" id="FirstName"/>
      Second Name:<input type="text" id="SecondName"/>
      <input type="button" value="Submit" onClick="validation()"/>
    </form>
</body>
</html>

Regards,
Kiran

Validation message

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