// JavaScript Document

//Constants
var alpha=new String("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz");
var num=new String("0123456789");

function reverse(str)
{
var s1=new String(str);
var s2=new String();
for(i=s1.length; i>=0; i--)
	s2+=s1.charAt(i);
return s2;
}

function ltrim(str)
{
var s=new String(str);
while(s.charAt(0) == " ")
      	s=s.replace(" ","");
return s;
}

function rtrim(str)
{
var s=new String(str);
s=reverse(s);
while(s.charAt(0) == " ")
      	s=s.replace(" ","");
s=reverse(s);
return s;
}

function trimLR(str)
{
var s=new String(str);
s=ltrim(s);
s=rtrim(s);
return s;
}
//Function to check empty string
function isEmpty(str)
{
var s= new String(str);
s=trimLR(s);
if(s.length==0)
   return true;
else
   return false;
}
//Function to check whether string contains any invalid character.
function isAllCharsIn(str1, str2)
{
var s1=new String(str1);
var s2=new String(str2);
var status=true;
if(isEmpty(s1))
  status=false;
else
   for(i=0; i<s1.length; i++)
	   if(s2.indexOf(s1.charAt(i)) == -1) { status=false; break; }
return status;
}

//Function to check for valid email ID
function isEmailId(str)
{
var s=new String(str);
var chars=new String("@.-_");
if(isAllCharsIn(s,alpha+num+chars))
   if(s.indexOf("@") != -1)
	  if(s.indexOf(".") != -1)
	      return true;
return false;
}