Simple example on how to use the ACE Editor

ACE.js

var dom = require("ace/lib/dom");

require("ace/commands/default_commands").commands.push({
    name: "Toggle Fullscreen",
    bindKey: "F11",
    exec: function(editor) {
        dom.toggleCssClass(document.body, "fullScreen");
        dom.toggleCssClass(editor.container, "fullScreen");
        editor.resize();
    }
});

var editor = ace.edit("editor");
editor.setTheme("ace/theme/github");
editor.getSession().setMode("ace/mode/markdown");

var converter = Markdown.getSanitizingConverter();

editor.on("change", function(e){
  var strHTML = converter.makeHtml(editor.getValue());
	$('#editor_preview').html(strHTML);
});

function undo() {
	editor.undo();
}

function redo() {
	editor.redo();
}