10 great javascript functions

I haven't found time to go back and discuss these functions, but here they are.

//this function is case insensitive
String.prototype.beginsWith = function(t) {
    return (t.toLowerCase() == this.substring(0, t.length).toLowerCase());
}
String.prototype.trim = function() {
 return this.replace(/^\s+|\s+$/g,"");
}
String.prototype.ltrim = function() {
 return this.replace(/^\s+/,"");
}
String.prototype.rtrim = function() {
 return this.replace(/\s+$/,"");
}

function isInt (str)
{
 var i = parseInt (str);
 if (isNaN (i))
  return false;
 if (i.toString() != str)
  return false;
 return true;
}

function alert_obj(obj)
{
 var str2='';
 for(s in obj)
  str2+=  "obj["+s+"]"+obj[s]+"\n";
 alert(str2);
}

function xml_text_node(elem,nam)
{
 try{
  return elem.getElementsByTagName(nam)[0].firstChild.nodeValue;
 }
 catch(e){
  return "";
 }
}

function count_children(myElement)
{
   if (!myElement)
    return 0;
   var count=0;
   var child = myElement.firstChild;
   while (child!=null)
   {
    count++;
    child = child.nextSibling;
   }
   return count;
}

function removeChildren(list)
{
 if (list==null) return;
 var child = list.firstChild;
 while(child!=null)
 {
  list.removeChild(child);
  child = list.firstChild;
 }
}

function DOMelement(txt)
{
 var o = new Object();
 o.elementname   = txt;
 o.attributes = new Object();
 o.innerHTML  = '';
 o.innerText  = '';
 o.createElement = function()
 {
  var attribute_str = '';
  for(attrib_name in o.attributes)
   attribute_str+= attrib_name+"='"+escape(o.attributes[attrib_name])+"'";

  var element;
  try
  {//IE
   element = document.createElement("<"+o.elementname+" "+attribute_str);
  }
  catch (e)
  {
   element = document.createElement( o.elementname );
   for(attrib_name in o.attributes)
    element.setAttribute( attrib_name , o.attributes[attrib_name] );
  }
  if (o.innerHTML.length>0)
   element.innerHTML = o.innerHTML;
  else if (o.innerText.length>0)
   element.appendChild( document.createTextNode(o.innerText) );
  return element;
 }

 o.setAttribute = function(attribute,attribute_value)
 {
  o.attributes[attribute] = attribute_value;
 }
 return o;
}

usage:
var e = DOMelement('div');
e.setAttribute('asdfs','asdfs');
e.setAttribute('asdfs','asdfs');
e.setAttribute('asdfs','asdfs');
var element = e.createElement();

This is the ultimate, because it works in IE as well as compliant browsers.