JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="newContent"></textarea>
        <input type="button" id="editPanel" value="Edit content of panel" />
        <div id="pnlRegular"></div>

JavaScript

YUI().use('panel', function(Y) {

                var pnlRegular = new Y.Panel({
                    srcNode : "#pnlRegular",
                    render : true,
                    visible : false,
                    width : 500,
                    centered : true,
                    modal : false,
                    headerContent : 'HEADER',
                    footerContent : 'FOOTER',
                    buttons : [{
                        value : '<img src="http://docs.gimp.org/en/images/dialogs/stock-edit-16.png"/>',
                        section : 'header',
                        action : function(e) {
                            e.preventDefault();
                            alert('edit clicked');
                        }
                    }, {
                        type : "close",
                        section : 'header'
                    }, {
                        value : "RESIZE",
                        section : 'footer',
                        action : function(e) {
                            e.preventDefault();
                            if(pnlRegular.get('bodyContent').get('textContent')[0] == pnlRegular.get('smallContent')) {
                                pnlRegular.set('bodyContent', pnlRegular.get('largeContent'));
                            } else {
                                pnlRegular.set('bodyContent', pnlRegular.get('smallContent'));
                            }

                        }
                    }]

                });

                pnlRegular.show();

                Y.one("#editPanel").on("click", function() {
                    var newContent = Y.one('#newContent').get('value');
                    var subNewContent = newContent.substring(0, 96) + ' ...';
                    pnlRegular.set('largeContent', newContent);
                    if(newContent.length < 100) {
                        pnlRegular.set('smallContent', newContent);
                    } else {
                       ...