[vanoha]

Что я делаю не так?

function Strong(thisob){
	var PosStart = 0, PosEnd=0, sel, range;
	if (window.getSelection) { 
		sel = window.getSelection();
		if (sel.rangeCount){ 
			range = sel.getRangeAt(0);
		  	if (range.commonAncestorContainer.parentNode == thisob){
				PosStart = range.startOffset;
				PosEnd = range.endOffset;
			}
      	}
    }
	var dovs = $(thisob).html().slice(0, PosStart);
	var posvs = $(thisob).html().slice(PosEnd);
	$(thisob).html(dovs+"<strong>"+range.toString()+"</strong>"+posvs);
}