Imagen execCommand

function insertHTML(img) {
  var id = "rand" + Math.random();
  var doc = document.getElementById("editor");
  doc = doc.document ? doc.document : doc.contentWindow.document;
  img = "<img src='" + img + "' id=" + id + ">";

  if(document.all) {
    var range = doc.selection.createRange();
    range.pasteHTML(img);
    range.collapse(false);
    range.select();
  } else {
    doc.execCommand("insertHTML", false, img);
  }
  return doc.getElementById(id);
};
Doubtful Dotterel