function BSF_initBrowserType() 
{
	this.IE		= false;
	this.NS4	= false;
	this.NS6	= false;
	
	if (document.all)
	{
		// IE4, IE5.X
		this.Name	= "IE";
		this.IE		= true;
	} 
	else if (document.layers) 
	{
		// NS4.X
		this.Name	= "NS4";
		this.NS4		= true;
	} 
	else if (document.getElementById) 
	{
		// NS6
		this.Name	= "NS6";
		this.NS6		= true;
	}
}

var BSF_BrowserType = new BSF_initBrowserType();

function BSF_getObjectById(id) {
	var obj = null;
	if (BSF_BrowserType.IE) 
	{
		obj=document.all[id];
	}
	else if (BSF_BrowserType.NS6) 
	{
		obj=document.getElementById(id);
	}
	else if (BSF_BrowserType.NS4) 
	{
		obj=document.layers[id];
	}
	
	return obj;
}

function BSF_getTextFromObj(obj)
{
      
   if (   BSF_BrowserType.IE
         ||
         BSF_BrowserType.NS6
      )
   {
      return obj.innerHTML;
   }
   else
   {
      return false;
   }
}

document.getElementById('ID_des_Elements')

   if (document.getElementById(id)=='[object HTMLInputElement]')
   {
         ... Formularelement gefunden ...
   }

function BSF_getObjectById(id)
{
   if (document.layers) return document.layers[id];
   if (document.all && !document.getElementById) return document.all[id];
   if (document.getElementById) return document.getElementById(id);
   return null;
}

function BSF_getTextFromObj(obj)
{
   if (var obj = BSF_getObjectById(obj)) {
     return (obj.value) ? obj.value : (obj.innerHTML ? obj.innerHTML : false);
   }
   else return false;
}

if(obj instanceof forms)
    //  Formular oder Formularelement