// JavaScript Document

function isnumber(s)
{
	while(s.length)
	{
		switch(s.substring(0,1))
		{
			case '0':break;
			case '1':break;
			case '2':break;
			case '3':break;
			case '4':break;
			case '5':break;
			case '6':break;
			case '7':break;
			case '8':break;
			case '9':break;
			default:return false;
		}
		s=s.substring(1,s.length);
	}
	return true;
}

function check_number(textbox, default_value)
{
	if(!isnumber(textbox.value))
	{
		alert('Chi duoc nhap gia tri so!');
		textbox.value=default_value;
		textbox.select();
		return false;
	}
	return true;
}
/*
function trimAll(sString) 
{
	while (sString.substring(0,1) == ' ')
	{
		 sString = sString.substring(1, sString.length);
	}
	while (sString.substring(sString.length-1, sString.length) == ' ')
	{
	 	sString = sString.substring(0,sString.length-1);
	}
	return sString;
}*/
/**
*
*  Javascript trim, ltrim, rtrim
*  http://www.webtoolkit.info/
*
**/
 
function trimAll(str, chars) {
	return ltrim(rtrim(str, chars), chars);
}
 
function ltrim(str, chars) {
	chars = chars || "\\s";
	return str.replace(new RegExp("^[" + chars + "]+", "g"), "");
}
 
function rtrim(str, chars) {
	chars = chars || "\\s";
	return str.replace(new RegExp("[" + chars + "]+$", "g"), "");
}

function is_empty(obj) // obj la textbox hoac textare
{
    if(trimAll(obj.value)=='') 
        return true;
    else
        return false;    
}

function IsEmail(str) {

		var at="@"
		var dot="."
		var lat=str.indexOf(at)
		var lstr=str.length
		var ldot=str.indexOf(dot)
		if (str.indexOf(at)==-1){
		   return false
		}

		if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr){
		   return false
		}

		if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
		    return false
		}

		 if (str.indexOf(at,(lat+1))!=-1){
		    return false
		 }

		 if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
		    return false
		 }

		 if (str.indexOf(dot,(lat+2))==-1){
		    return false
		 }
		
		 if (str.indexOf(" ")!=-1){
		    return false
		 }

 		 return true					
	}