function trim(inputString) {   
   if (typeof inputString != "string") { return inputString; }
   var ketqua = inputString;
   var ch = ketqua.substring(0, 1);
   while (ch == " ") { 
      ketqua = ketqua.substring(1, ketqua.length);
      ch = ketqua.substring(0, 1);
   }
   ch = ketqua.substring(ketqua.length-1, ketqua.length);
   while (ch == " ") { 
      ketqua = ketqua.substring(0, ketqua.length-1);
      ch = ketqua.substring(ketqua.length-1, ketqua.length);
   }
   while (ketqua.indexOf("  ") != -1) {
      ketqua = ketqua.substring(0, ketqua.indexOf("  ")) + ketqua.substring(ketqua.indexOf("  ")+1, ketqua.length); 
   }
   return ketqua; 
} 

function checkEmail(s)
{
	var the_email=s
	var char_at=the_email.lastIndexOf("@");
	var the_dot=the_email.indexOf(".");
	var a_space=the_email.indexOf(" ")
	if((char_at!=-1)&&(char_at!=0)&&(the_dot!=-1)&&	(the_dot>char_at+1)&&(the_dot<the_email.length-1)&&(a_space==-1))
	{		
		return true;//dung kieu email 
	}	else	return false; // khong dung kieu email	
}

function isPhoneNumber(sIn)
{
	//if (typeof(sIN)!="string") return false;
	var ch;
	var n=sIn.length;
	for (var i=0; i<n; i++){
		ch=sIn.substring(i,i+1);		
		if (isNaN(ch)&& (ch!="-") && (ch!=".")) return false;
	}
	return true;
}