function blink(elId){
  var html = '';
  if(document.all){
    html += 'var bl = document.all.' + elId + ';';
  }
  else if(document.getElementById){
    html += 'var bl = document.getElementById("' + elId + '");';
  }
  html += 'bl.style.visibility = ' + 'bl.style.visibility == "hidden" ? "visible" : "hidden"';
  if(document.all || document.getElementById){
    setInterval(html, 500);
  }
}
function init(){
  blink('Text');
}
onload=init;