function check_all()
{
	var checks = document.getElementsByName('chk[]');
	var boxLength = checks.length;
	for ( i=0; i < boxLength; i++ ) 
	{
      		checks[i].checked = true;
    }
	
		
}
function uncheck_all()
{
	var checks = document.getElementsByName('chk[]');
	var boxLength = checks.length;
	for ( i=0; i < boxLength; i++ ) 
	{
		checks[i].checked = false;
	}
}
function delete_all(url)
{
	var count_chk=0;
	count_chk=checkbox_status();
	if(count_chk==0)
	{
		alert('Please check atleast one check box ');
		
	}
	else
	{
	if(confirm('Do you really want to delete the selected messages from your inbox? This can not be undone!!'))
	{

	document.myform.action =url;
		document.myform.submit();
	 
	}
	}	
}	
function checkbox_status()
{
			var checks = document.getElementsByName('chk[]');
			var boxLength = checks.length;
			var count_chk=0;
			for ( i=0; i < boxLength; i++ ) 
		 	{
        		if(checks[i].checked == true)
        		 count_chk++;        		
      		}
      		
return count_chk;
}