// DF1.1 :: domFunction 
// *****************************************************
// DOM scripting by brothercake -- http://www.brothercake.com/
// GNU Lesser General Public License -- http://www.gnu.org/licenses/lgpl.html
//******************************************************


//DOM-ready watcher
function domFunction(f, a)
{
/*

You can treat it essentially the same as a regular onload function except that - if you're going to manipulate 
(eg, read from or append to) any existing HTML elements other than the body, you must also test for those elements before calling your script.

And for this purpose the constructor takes an optional second argument - an object-literal which defines the elements or 
collections that the script should test before trying to call the function. The following call tests for an element with the id 'poster' and
an element with the tag 'h1'.

function domFunction(myfunc, { 'poster' : 'id', 'h1' : 'tag' })

Each name/value pair should be either the ID of an element, followed by the value "id", to test whether that element exists; or
the tag name of an element, followed by the value "tag", to test whether that collection has any members.

*/

	//initialise the counter
	var n = 0;
	
	//start the timer
	var t = setInterval(function()
	{
		//continue flag indicates whether to continue to the next iteration
		//assume that we are going unless specified otherwise
		var c = true;

		//increase the counter
		n++;
	
		//if DOM methods are supported, and the body element exists
		//(using a double-check including document.body, for the benefit of older moz builds [eg ns7.1] 
		//in which getElementsByTagName('body')[0] is undefined, unless this script is in the body section)
		if(typeof document.getElementsByTagName != 'undefined' && (document.getElementsByTagName('body')[0] != null || document.body != null))
		{
			//set the continue flag to false
			//because other things being equal, we're not going to continue
			c = false;

			//but ... if the arguments object is there
			if(typeof a == 'object')
			{
				//iterate through the object
				for(var i in a)
				{
					//if its value is "id" and the element with the given ID doesn't exist 
					//or its value is "tag" and the specified collection has no members
					if
					(
						(a[i] == 'id' && document.getElementById(i) == null)
						||
						(a[i] == 'tag' && document.getElementsByTagName(i).length < 1)
					) 
					{ 
						//set the continue flag back to true
						//because a specific element or collection doesn't exist
						c = true; 

						//no need to finish this loop
						break; 
					}
				}
			}

			//if we're not continuing
			//we can call the argument function and clear the timer
			if(!c) { f(); clearInterval(t); }
		}
		
		//if the timer has reached 60 (so timeout after 15 seconds)
		//in practise, I've never seen this take longer than 7 iterations [in kde 3 
		//in second place was IE6, which takes 2 or 3 iterations roughly 5% of the time]
		if(n >= 60)
		{
			//clear the timer
			clearInterval(t);
		}
		
	}, 250);
};