function isEmpty(s){ 

	s=deleteSpaces(s);

	return s.length==0;

}

function deleteSpaces(s){

	var re=/\s/g;

	s=s.replace(re,"");

	return s;

}

function trim(s){

	var re=/^\s+/;

	s=s.replace(re,"");

	re=/\s+$/;

	s=s.replace(re,"");

	return s;

}

function deleteFirstZero(s){

	s=""+s;

	var re=/^0+/;

	s=s.replace(re,"");

	return s;

}

function isNativeNumber(s){

	s = trim(s);

	var re=/[\D]/g;

	var r=s.replace(re,"");

	return r==s && r!="";

}

function isNumber(s){

	s = trim(s);

	return !isNaN(Number(s)) && s!="";

}

function isEmail(s){

	s = trim(s);

	emailPat=/^(.+)@(.+)\.(.+)$/;

	var a=s.match(emailPat);

	if (a==null){

		emailPat = /^(.+)@(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/;

		a=s.match(emailPat);

	}

	return (a!=null);

}

var const_days = [0,31,28,31,30,31,30,31,31,30,31,30,31];

function isDate(d, m, y){

	d = deleteFirstZero(d);

	m = deleteFirstZero(m);

	y = deleteFirstZero(y);

	b = isNativeNumber(d) && isNativeNumber(m) && isNativeNumber(y) && m>0 && m<13 && d>0 && y>0;

	if (b){

		b = (d<=const_days[m]) || (m==2 && d==29 && (y%4==0))

	}

	return b;

}

/**

* check date and return the right dates

* using: var ret=["","", ""]

* isDMYDate("12-12-2001", ret)

*/

function isDMYDate(s, ret){

	s = deleteSpaces(s);

	var re=/-/g;

	s = s.replace(re, "/");

	dmy=s.split("/");

	b = dmy.length==3

	if (b){

		b = isDate(dmy[0],dmy[1],dmy[2]);

		if (b){

			ret[0] = s;

			ret[1] =dmy[0]+"-"+dmy[1]+"-"+dmy[2];

			ret[2] =dmy[2]+"-"+dmy[1]+"-"+dmy[0];

		}

	}

	return b;

}

/**

* check date and return the right dates

* using: var ret=["","",""]

* isMDYDate("12-12-2001", ret)

*/

function isMDYDate(s, ret){

	s = deleteSpaces(s);

	var re=/-/g;

	s = s.replace(re, "/");

	dmy=s.split("/");

	b = dmy.length==3

	if (b){

		b = isDate(dmy[1],dmy[0],dmy[2]);

		if (b){

			ret[0] = s;

			ret[1] =dmy[0]+"-"+dmy[1]+"-"+dmy[2];

			ret[2] =dmy[2]+"-"+dmy[0]+"-"+dmy[1];

		}

	}

	return b;

}