Common Javascript for Validation

dhage.prashant01 wrote:

txtuserid.Attributes.Add("onblur", "check(document.getElementById('txtuserid'));")

This is where you are doing wrong.

you are expecting an object of textbox, based on which value you prompt an alert.

Instead use 'this'. it will pass the full textbox object and you can use it the same way as if its selected using document.getElementById

Thus the change would be:

txtuserid.Attributes.Add("onblur", "check(this);")

thanks guys

I have done something like that

.js file

function chkBlank(objId, lblText)
{
    if(objId.value == "")
    {
        alert("Please enter " + lblText);
        objId.focus();
        return false; 
    }
    else
    {
        return true;
    }
}

.aspx file

<script type="text/javascript" src="../JS/Validation.js"></script>
    <script type="text/javascript" language="javascript">

function Validate()
{
        if(chkBlank(document.getElementById('txtuserid'),document.getElementById('lblUserId').innerText) == false){return false;}
        if(chkBlank(document.getElementById('txtpwd'),document.getElementById('lblPwd').innerText) == false){return false;}
}

.aspx.vb

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        txtuserid.Focus()
        imgblogin.Attributes.Add("onclick", "javascript:return Validate();")
End Sub

You've been given good answers, but I'd like to cover why document.getElementById didn't work with txtUserId.

In HTML (as in so many other programming areas), an ID must be unique, and ASP.NET allows you to use the same ID in many different controls that are placed on a screen. This means that there has to be some mechanism that transforms the ID into something unique, and ASP.NET achieves this by mangling the name - this is why there is an property of each control called ClientID - this can be used to find out what the client side ID is.