/**
  * Try this, see if it does what you're looking for...
  */
function updateHeight () {
  var y, _y = 1000, d=document.getElementsByTagName("body")[0];
  if (d.scrollHeight - d.scrollTop <= 1000)
     alert("not much more scroll to go!\n"+(d.scrollHeight - d.scrollTop)+"px left");
}






getPageHeight() appears to be working incorrectly. It is reporting a max of 686, while the getScrollHeight() is reporting in the thousands (appears correct). If getPageHeight() is just reporting the viewable area, how might i get it to report the *actual* page height.

// These two functions are based on code from
// http://www.quirksmode.org/viewport/compatibility.html
function getPageHeight(){
	var y;
	var test1 = document.body.scrollHeight;
	var test2 = document.body.offsetHeight;

	if (test1 > test2) { // all but Explorer Mac
		y = document.body.scrollHeight;
	} else { // Explorer Mac; would also work in Explorer 6 Strict, Mozilla and Safari
		y = document.body.offsetHeight;
	}

	return parseInt(y);
}

function _getWindowHeight(){
	if(self.innerWidth) {
		frameWidth = self.innerWidth;
		frameHeight = self.innerHeight;
	} else if (document.documentElement && document.documentElement.clientWidth) {
		frameWidth = document.documentElement.clientWidth;
		frameHeight = document.documentElement.clientHeight;
	} else if (document.body) {
		frameWidth = document.body.clientWidth;
		frameHeight = document.body.clientHeight;
	}

return parseInt(frameHeight);
}


function getScrollHeight(){
	var y;

	// all except Explorer
	if(self.pageYOffset) {
		y = self.pageYOffset;
	} else if (document.documentElement && document.documentElement.scrollTop) {
		y = document.documentElement.scrollTop;
	} else if (document.body) { // all other Explorers
		y = document.body.scrollTop;
	}

	return parseInt(y)+_getWindowHeight();
}