function winrem(a) {
  a.parentNode.nextSibling.style.display = 'none';
  a.parentNode.style.display = 'none';
}

function jWnd(params) {
  params = params || {};
  k = (!-[1,]) ? 0 : 8;
  var e = document.createElement('div');
  var leftmargin = ((document.body.offsetWidth / 2) - (params.w / 2));
  var topmargin = ( ((!-[1,]) ? document.body.offsetHeight : window.innerHeight) / 2) - (params.h / 2)
  var headerinner = params.header ? '<div style="font-weight: bold;color: white; position: absolute; width: ' + (params.w + k) + '; height: 20px; background: #b52828; top: ' + (topmargin - 20) + '; left: ' + leftmargin + 'px;"><span style="float:left">' + params.header + '</span><a style="float:right;color:white;" href="javascript://" onclick="winrem(this);">X</a></div>' : '';
  var content = params.content ? params.content : '<iframe src="' + params.url + '" height="100%" width="100%" frameborder="0"></iframe>';
  e.innerHTML = headerinner + '<div style="border:4px solid #00b4ff;color: white; position: absolute; width: ' + params.w + '; height: ' + params.h + '; background: #3e3e3e; top: ' + topmargin + '; left: ' + leftmargin + 'px;">' + content + '</div>';
  document.body.appendChild(e);
}

<a href="javascript://" onclick="jWnd({w: 500,h: 300,content: 'Ваш текст',header: 'Заголовок''});"> Открыть текст в jWnd </a>