function ChangeImg() {
 if(document.images) {
  eval("document.getElementById('"+ChangeImg.arguments[0]+"').src=('"+ChangeImg.arguments[1]+"')");
 }
}

function preload() {
  if (document.images) {
    var imgsrc = preload.arguments;
    arr=new Array(imgsrc.length);
    for (var j=0; j<imgsrc.length; j++) {
      arr[j] = new Image;
      arr[j].src = imgsrc[j];
    }
  }
}

function checkSubscribeForm() {
	enterprise = document.getElementById('enterprise').value;
	lastname = document.getElementById('lastname').value;
	firstname = document.getElementById('firstname').value;
	middlename = document.getElementById('middlename').value;
	position = document.getElementById('position').value;
	subscriberEmail = document.getElementById('subscriberEmail').value;
	
	if(trim(enterprise).length == 0
	|| trim(lastname).length == 0
	|| trim(firstname).length == 0
	|| trim(middlename).length == 0
	|| trim(position).length == 0
	|| trim(subscriberEmail).length == 0) 
	{
		alert('Все поля формы обязательны');
		return false;
	}
	
	if(!isValidEmail(subscriberEmail))
	{
		alert('Введите корректный E-mail адрес');
		return false;
	}
	
	return true;
}


//function to check valid email address
function isValidEmail(strEmail){
  validRegExp = /^[^@]+@[^@]+.[a-z]{2,}$/i;

   // search email text for regular exp matches
   if(strEmail.search(validRegExp) == -1) 
   {
      return false;
   } 
   
   return true; 
}



function checkSendForm() {
		senderValue = document.getElementById('senderName').value;
		senderContacts = document.getElementById('senderContacts').value;
		senderMessage = document.getElementById('senderMessage').value;
				
		if (trim(senderValue).length == 0) {
				alert('Поле "Представьтесь" не заполнено');
				return false;
		}
		
		if (trim(senderContacts).length == 0) {
				alert('Поле "Ваши контактные данные" не заполнено');
				return false;
		}
		
		if (trim(senderMessage).length == 0) {
				alert('Поле "Текст сообщения" не заполнено');
				return false;
		}
	return true;
}

function trim(string){
	return string.replace(/(^\s+)|(\s+$)/g, "");
}