function addEvent(el, event, func) { 
    if (el.addEventListener) {
      el.addEventListener(event, func, false);
    } else {
      el.attachEvent('on'+event, func);
    }
  }

  var search_form = document.getElementById('search_form');
  var create_form = document.getElementById('create_form');
  var email_form = document.getElementById('email_form');

  addEvent(search_form, 'submit', function(e) {
	var search_bar = document.getElementById('Search_bar');
	if (search_bar.value == ''){
		e.returnValue = false;
		if (e.preventDefault) {
			e.preventDefault();
		}
		search_bar.focus();	
	}
  });
  
    addEvent(email_form, 'submit', function(e) {
	var email = document.getElementById('email');
	var password = document.getElementById('password');
	if (email.value == '' || password.value == ''){
		e.returnValue = false;
		if (e.preventDefault) {
			e.preventDefault();
		}
		if (email.value == ''){
			email.focus();
		}
		else {
			password.focus();
		}
	}
  });
  
    addEvent(create_form, 'submit', function(e) {
	var prenom = document.getElementById('prenom');
	var nom = document.getElementById('nom');
	if (prenom.value == '' || nom.value == ''){
		e.returnValue = false;
		if (e.preventDefault) {
			e.preventDefault();
		}
		if (prenom.value == ''){
			prenom.focus();
		}
		else {
			nom.focus();
		}		
	}
  });