function ValidateUsername(strng)
{
var error = “”;
if (strng.trim() == “”) {
error = “Please Enter Username.\n”;
}
if(error==”")
{
if ((strng.length < 4) || (strng.length > 20))
{
error = “Please Enter Minimum 4 And Maximum 20 Charactors.\n”;
}
}
if(error==”")
{
var ValidChars = “._0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ”;
var IsNumber=true;
var Char;
var str=strng;
var dot=”.”;
var lstr=str.length;
var ldot=str.indexOf(dot);
for (i = 0; i < str.length && IsNumber == true; i++)
{
Char = str.charAt(i);
if (ValidChars.indexOf(Char) == -1)
{
error=”Username Should  Alpha-numeric,Underscore And Dot Only”;
}//end if
}//end for
}
if(error==”")
{
var sText=strng;
Char = sText.charAt(0);
ValidChars = “._”;
if (ValidChars.indexOf(Char) != -1)
{
error=”First Letter Should  Alpha-numeric Only”;
}
}

if(error==”")
{
var str=”"
for (i = 0; i < sText.length ; i++)
{
Char = sText.charAt(i);
if((sText.charAt(i)==”_” && sText.charAt(i+1)==”_”)||(sText.charAt(i)==”.” && sText.charAt(i+1)==”.”))
{
error=”Consecutive Special Charactors Not Allow”;
}
}
}
return error;
}