// Function $ like in Prototype framework. 
// Unfortunately prototype not works with liferay in IE.
//    id - id of the element.
function $(id) {
return document.getElementById(id);
}
// Submit form by it's id.
//    id - id of the form.
function submitFormById(id) {
var form = $(id);	
if (form) {
form.submit();	
}	
}
//Submit form by it's name.
//name - name of the form.
function submitFormByName(name) {
var form = document.forms[name];
if (form) {
form.submit();	
}	
}
// Preload image.
//    src - url of image.
function preloadImage(src) {
if (document.images) {
var image = new Image();
image.src = src;
}
}
// Browser-compatible function for adding window onload event listeners.
//    func - function to execute when window has been loaded.
function addOnLoadEvent(func) {
if (window.addEventListener) {
// W3C standard
window.addEventListener('load', func, false); // !!!! not 'onload'
} else if (window.attachEvent) {
// Microsoft
window.attachEvent('onload', func);
}
}
// Trim string.
//   string - string to trim.
//   result: trimmed string.
function trim(string) {
return string.replace(/(^\s+)|(\s+$)/g, "");
}
// Submit field (and form), that have hint value.
//    formId - id of the form, that contains field.
//    fieldId - id of the field.
function submitFieldWithHintValue(formId, fieldId) {
var field = $(fieldId);
if (field.value != field.title) {
submitFormById(formId);
}	
}
// Remove hint field class (grey letters).
//    id - id of the field object (<input>);
function removeFieldHintClass(id) {
var field = $(id);
if (field.value != field.title) {
removeClass(field, 'form-empty-field');
}	
}
// Add hint field class (grey letters).
//    id - id of the field object (<input>);
function addFieldHintClass(id) {
var field = $(id);
if (field.value == field.title) {
addClass(field, 'form-empty-field');		
}	
}
// Remove hint field value (like "Search..." at the search field).
//    id - id of the field object (<input>);
function removeFieldHintValue(id) {
var field = $(id);
if (field.value == field.title) {
field.value = "";
}
removeFieldHintClass(id);
}
// Add hint field value (like "Search..." at the search field).
//    id - id of the field object (<input>);
function addFieldHintValue(id) {
var field = $(id);
if (trim(field.value).length == 0) {
field.value = field.title;	
}
addFieldHintClass(id);
}
// Add class to element
//   element - html element.
//   clazz - class.
function addClass(element, clazz){
    var re = new RegExp("(^|\\s)" + clazz + "(\\s|$)", "g")
    if (re.test(element.className)) return
    element.className = (element.className + " " + clazz).replace(/\s+/g, " ").replace(/(^ | $)/g, "")
}
// Remove class from element
//   element - html element.
//   clazz - class.  
function removeClass(element, clazz){
    var re = new RegExp("(^|\\s)" + clazz + "(\\s|$)", "g")
    element.className = element.className.replace(re, "$1").replace(/\s+/g, " ").replace(/(^ | $)/g, "")
}