javascript selection anchorOffset, focusOffset

Return an integer count of characters or nodes from the beginning of the anchor or focus nodes of the selection (see anchorNode and focusNode properties). If the node is a text node, the offset unit is the character; if the node is an element node, the offset unit is the node. This behavior is similar to the offset properties of a Range object. Most typically, these values count characters within text node types. If the selection is set or extended via the addRange( ) method, these properties point to the node boundary offsets of the most recently added range.