function replaceTxtBack(){
  if(document.getElementById('newsletteremail').value==""){
    document.getElementById('newsletteremail').value="@";
  }
}
function replaceTxt(){
  if(document.getElementById('newsletteremail').value=="@"){
    document.getElementById('newsletteremail').value="";
  }
}

var text="";

function replaceTxtBack2(){
  if(document.getElementById('keyword').value==""){
    document.getElementById('keyword').value=text;
  }
}
function replaceTxt2(){
  if(document.getElementById('keyword').value=="hledaný výraz"){
    text=document.getElementById('keyword').value;
    document.getElementById('keyword').value="";
  }
  if(document.getElementById('keyword').value=="szukany wyraz"){
    text=document.getElementById('keyword').value;
    document.getElementById('keyword').value="";
  }
  if(document.getElementById('keyword').value=="searching expression"){
    text=document.getElementById('keyword').value;
    document.getElementById('keyword').value="";
  }
}
// JavaScript Document
function isEmail(who) {
	function isEmpty(who) {
		var testArr=who.split("");
		if(testArr.length==0)
			return true;
		var toggle=0;
		for(var i=0; i<testArr.length; i++) {
			if(testArr[i]==" ") {
				toggle=1;
				break;
			}
		}
		if(toggle)
			return true;
		return false;
	}

	function isValid(who) {
		var invalidChars=new Array("~","!","@","#","$","%","^","&","*","(",")","+","=","[","]",":",";",",","\"","'","|","{","}","\\","/","<",">","?");
		var testArr=who.split("");
		for(var i=0; i<testArr.length; i++) {
			for(var j=0; j<invalidChars.length; j++) {
				if(testArr[i]==invalidChars[j]) {
					return false;
				}
			}
		}
		return true;
	}

	function isfl(who) {
		var invalidChars=new Array("-","_",".");
		var testArr=who.split("");
		which=0;
		for(var i=0; i<2; i++) {
			for(var j=0; j<invalidChars.length; j++) {
				if(testArr[which]==invalidChars[j]) {
					return false;
				}
			}
			which=testArr.length-1;
		}
		return true;
	}

	function isDomain(who) {
		var invalidChars=new Array("-","_",".");
		var testArr=who.split("");
		if(testArr.length<2||testArr.length>4) {
			return false;
		}
		for(var i=0; i<testArr.length; i++) {
			for(var j=0; j<invalidChars.length; j++) {
				if(testArr[i]==invalidChars[j]) {
					return false;
				}
			}
		}
		return true;
	}


	var testArr=who.split("@");
	if(testArr.length<=1||testArr.length>2) {
		return false;
	}
	else {
		if(isValid(testArr[0])&&isfl(testArr[0])&&isValid(testArr[1])) {
			if(!isEmpty(testArr[testArr.length-1])&&!isEmpty(testArr[0])) {
				var testArr2=testArr[testArr.length-1].split(".");
				if(testArr2.length>=2) {
					var toggle=1;
					for(var i=0; i<testArr2.length; i++) {
						if(isEmpty(testArr2[i])||!isfl(testArr2[i])) {
							toggle=0;
							break;
						}
					}
					if(toggle&&isDomain(testArr2[testArr2.length-1]))
						return true;
					return false;
				}
				return false;
			}
		}
	}
}

/* With RegExp */
function isEmail2(who) {
	//var email=/^[A-Za-z0-9][\w-.]+[A-Za-z0-9]@[A-Za-z0-9]([\w-.]+[A-Za-z0-9]\.)+([A-Za-z]){2,4}$/i;
	var email=/^[a-zA-Z0-9][a-zA-Z0-9_\+-]+(\.[a-zA-z0-9_\+-]+)*@[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)*\.[a-zA-Z]{2,4}$/i;
	return(email.test(who));
}