Caret Position in Textarea using IE8 and Javascript

I need to find the current caret (cursor) position in a textarea in Internet Explorer 8.  The attached code works in firefox, but not in IE8.  It has provision for IE but I think it only works in IE7, there is a problem with the createRange in IE8 when nothing is actually selected.

I need the position of the caret, relative to the start of the text in the textarea, the content may include new lines, etc.

// Function used to get caret's position
getCaretPosition = function(oField)
{
	// Initialize
	var iCaretPos = 0;

	// IE Support
	if (document.selection)
	{
		oField.focus ();
		
		// To get cursor position, get empty selection range
		var oSel = document.selection.createRange();

		// Move selection start to 0th position
		oSel.moveStart("character", 0 - oField.value.length);

		// The caret position is selection length
		iCaretPos = oSel.text.length;
	}
	// Firefox support
	else if (oField.selectionStart || oField.selectionStart == "0")
	{
		iCaretPos = oField.selectionStart;
	}

	// Return results
	return (iCaretPos);
}

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