ReFwdFormatter Demo

var refwdformatter = {

editing: false,

format: function (htmlMode) {

if (refwdformatter.editing) {
      return;
    }
    refwdformatter.editing = true;

//var prefs = Components.classes["@mozilla.org/preferences-service;1"].getService(Components.interfaces.nsIPrefService).getBranch("extensions.refwdformatter.");
    var ret = true; // prefs.getBoolPref("replytext.on");
    var reh = true; // prefs.getBoolPref("replyhtml.on");
    var lit = true; // prefs.getBoolPref("listtext.on");
    var lih = true; // prefs.getBoolPref("listhtml.on");
    var fwd = true; // prefs.getBoolPref("fwdsubject.on");

var t = 1; //gMsgCompose.type;
    var msgHtml = htmlMode; //gMsgCompose.composeHTML;

if (fwd && (t == 3 || t == 4)) {
      // Foward (3: ForwardAsAttachment, 4: ForwardInline)
      document.getElementById("msgSubject").value = document.getElementById("msgSubject").value.replace(/^\[/, "").replace(/\]$/, "");
    } else if ((ret || reh || lit || lih) && (t == 1 || t == 2 || t == 6 || t == 7 || t == 8 || t == 13)) {
      // Reply (1: Reply, 2: ReplyAll, 6: ReplyToSender, 7: ReplyToGroup, 8: ReplyToSenderAndGroup, 13: ReplyToList)
      var b = htmlMode ? document.getElementById("content-html-mail") : document.getElementById("content-text-mail"); //document.getElementById("content-frame").contentDocument.body;
      var h = b.innerHTML;
      ///// If you develop and test this add-on logic code, remove the following comment-out temporarily to get the whole html source of the current mail.
      /////b.innerHTML = h.replace(/[&"'<>]/g, function(m) { return { "&": "&amp;", '"': "&quot;", "'": "&#39;", "<": "&lt;", ">": "&gt;" }[m]; });
      /////return;
      
      // If you would like to debug the following code, use console.log() function and open DevTools.

/// [--- liveweave debug 1 - START copy here ---] 
      if (h !== "<br>") {

if ((ret || lit) && !msgHtml) {

if (b.hasChildNodes()) {
            var children = b.childNodes;
            //console.log(children);

var isFirstChildren = true;
            var brCounter = 2;  // There should be two <br> tags as FirstChildren in text-mail.
            for (var i = 0; i < children.length; i++) {

if (brCounter <= 0) isFirstChildren = false;
              var curChildNode = children[i];

if (curChildNode.nodeType === Node.TEXT_NODE) {
                //console.log(curGChildNode); 
                refwdformatter.removeQuoteMarksInTextMessage(curChildNode);  // Basically, this code-block won't be run.

} else {
                //console.log(curChildNode.tagName);
                switch (curChildNode.tagName) {

case "BR":
                    if (isFirstChildren) {
                      brCounter--;
                    }
                    break;

case "SPAN":
                  case "DIV":
                    if (isFirstChildren) isFirstChildren = false;
                    if (curChildNode.hasChildNodes()) {
                      var grandChildren = curChildNode.childNodes;
                      //console.log(grandChildren);
                      for (var n = 0; n < grandChildren.length; n++) {
                        var curGChildNode = grandChildren[n];
                        if (curGChildNode.nodeType === Node.TEXT_NODE) {
                          //console.log(curGChildNode); 
                          refwdformatter.removeQuoteMarksInTextMessage(curGChildNode);
                        }
                      }
                    }
                    break;

default:
                    if (isFirstChildren) isFirstChildren = false;
                    break;
                }

}

refwdformatter.addLineBreakJustInCase(brCounter);
          }

} else if ((reh || lih) && msgHtml) {

if (b.hasChildNodes()) {
            var childNodes = b.childNodes;
            //console.log(childNodes);
            var is1stChild = true;
            for (var l = 0; l < childNodes.length; l++) {
              if (childNodes[l].tagName == "BLOCKQUOTE") {
                is1stChild = false;
                // Replace the first <blockquote> tag with new <div> tag
                var newdiv = document.createElement("div");
                while (childNodes[l].firstChild) {
                  newdiv.appendChild(childNodes[l].firstChild); // *Moves* the child
                }
                newdiv.setAttribute('class', 'replaced-blockquote');
                for (var index = childNodes[l].attributes.length - 1; index >= 0; --index) {
                  newdiv.attributes.setNamedItem(childNodes[l].attributes[index].cloneNode());
                }
                childNodes[l].parentNode.replaceChild(newdiv, childNodes[l]);
                break;
              }
              if (!is1stChild) break;
            }

var resethtml = b.innerHTML;
            b.innerHTML = resethtml;  // To redraw. If there is not this code, the <div> tag width will shirink - I do not know why.

refwdformatter.addLineBreakJustInCase(brCount);         }
        }

refwdformatter.initCursorPosition();

}
      /// [--- liveweave debug 1 - END copy here ---] 
    }
    window.setTimeout(function () {
      refwdformatter.editing = false;
    }, 700);
  },

removeQuoteMarksInTextMessage: function (curNode) {
    /// [--- liveweave debug 2 - START copy here ---] 
    //console.log(curNode.previousSibling);
    if ((curNode.previousSibling === null) ||
        (curNode.previousSibling.tagName === "BR")) {
      //console.log(curNode.data);
      curNode.data = curNode.data.
        replace(/^> {2}/g, " ").
        replace(/^> /g, "").
        replace(/^>((>)+) /g, "$1 ").
        replace(/^>((>)+)$/g, "$1 ");
      //console.log(curNode.data);
    }
    /// [--- liveweave debug 2 - END copy here ---] 
  },
 
  addLineBreakJustInCase: function (brCounter) {
    //if (brCounter > 0) {
    //  var e = GetCurrentEditor();
    //  e.beginningOfDocument();
    //  while (brCounter > 0) {
    //    brCounter--;
    //    e.insertHTML("<br>");
    //  }
    //}
  },
  
  initCursorPosition: function () {
    //var e = GetCurrentEditor();
    //e.beginningOfDocument();
    //e.insertHTML(" ");
    //e.undo(1);
  },

onClick: function (htmlMode) {
    window.setTimeout(function () {
      refwdformatter.format(htmlMode);
    }, 700);
  }
};