HTML document selection using javascript

I use this javascript code to get the currently highlighted selection.

var selection = window.getSelection()

If the highlight is a section of text all within a <div>, how can I get the offset from the beginning of the <div> and the length of the highlight? (the length is not just the length of the text, it 开发者_JAVA百科should be the actual length of the html code for that text)

You can get the length of the selected HTML as follows:

function getSelectionHtml() {
    var sel, html = "";
    if (window.getSelection) {
        sel = window.getSelection();
        if (sel.rangeCount) {
            var frag = sel.getRangeAt(0).cloneContents();
            var el = document.createElement("div");
            el.appendChild(frag);
            html = el.innerHTML;
        }
    } else if (document.selection && document.selection.type == "Text") {
        html = document.selection.createRange().htmlText;
    }
    return html;
}

alert(getSelectionHtml().length);