   <script src="js/jquery.min.js"></script>
        <script src="../editormd.js"></script>
        <script type="text/javascript">
            var testEditor;

            function EditormdExtend() {

                this.extend("methodC", function() {
                    console.log("methodC");
                });

                // or
                testEditor.extend("methodA", function() {
                    console.log("methodA");
                });

                // one by one setting
           