function addWikiFormattingToolbar(textarea) {

  if ((typeof(document["selection"]) == "undefined")

   && (typeof(textarea["setSelectionRange"]) == "undefined")) {

    return;

  }

  var toolbar = document.createElement("div");

  toolbar.className = "wikitoolbar";

  function addButton(id, title, fn) {

    var a = document.createElement("a");

    a.href = "#";

    a.id = id;

    a.title = title;

    a.onclick = function() { try { fn() } catch (e) { } return false };

    a.tabIndex = 400;

    toolbar.appendChild(a);

  }

  function encloseSelection(prefix, suffix) {

    textarea.focus();

    var start, end, sel, scrollPos, subst;

    if (typeof(document["selection"]) != "undefined") {

      sel = document.selection.createRange().text;

    } else if (typeof(textarea["setSelectionRange"]) != "undefined") {

      start = textarea.selectionStart;

      end = textarea.selectionEnd;

      scrollPos = textarea.scrollTop;

      sel = textarea.value.substring(start, end);

    }

    if (sel.match(/ $/)) { // exclude ending space char, if any

      sel = sel.substring(0, sel.length - 1);

      suffix = suffix + " ";

    }

    subst = prefix + sel + suffix;

    if (typeof(document["selection"]) != "undefined") {

      var range = document.selection.createRange().text = subst;

      textarea.caretPos -= suffix.length;

    } else if (typeof(textarea["setSelectionRange"]) != "undefined") {

      textarea.value = textarea.value.substring(0, start) + subst +

                       textarea.value.substring(end);

      if (sel) {

        textarea.setSelectionRange(start + subst.length, start + subst.length);

      } else {

        textarea.setSelectionRange(start + prefix.length, start + prefix.length);

      }

      textarea.scrollTop = scrollPos;

    }

  }

  addButton("strong", "Bold text: '''Example'''", function() {

    encloseSelection("'''", "'''");

  });

  addButton("em", "Italic text: ''Example''", function() {

    encloseSelection("''", "''");

  });

  addButton("heading", "Heading: == Example ==", function() {

    encloseSelection("\n== ", " ==\n", "Heading");

  });

  addButton("link", "Link: [http://www.example.com/ Example]", function() {

    encloseSelection("[", "]");

  });

  addButton("code", "Code block: {{{ example }}}", function() {

    encloseSelection("\n{{{\n", "\n}}}\n");

  });

  addButton("hr", "Horizontal rule: ----", function() {

    encloseSelection("\n----\n", "");

  });

  addButton("np", "New paragraph", function() {

    encloseSelection("\n\n", "");

  });

  addButton("br", "Line break: [[BR]]", function() {

    encloseSelection("[[BR]]\n", "");

  });

  textarea.parentNode.insertBefore(toolbar, textarea);

}

// Add the toolbar to all <textarea> elements on the page with the class

// 'wikitext'.

var re = /\bwikitext\b/;

var textareas = document.getElementsByTagName("textarea");

for (var i = 0; i < textareas.length; i++) {

  var textarea = textareas[i];

  if (textarea.className && re.test(textarea.className)) {

    addWikiFormattingToolbar(textarea);

  }

}