var iframe = document.createElement('iframe'); 
iframe.src="http://www.1sucai.cn";  
document.body.appendChild(iframe);

try{  
   var iframe = document.createElement('<iframe name="ifr"></iframe>');  
  }catch(e){ 
    var iframe = document.createElement('iframe');  
    iframe.name = 'ifr';  
 }

if(ie && version < 9) {
  var iframe = document.createElement('<iframe src="http://www.1sucai.cn"></iframe>');
} else {
  var iframe = document.createElement('iframe');
  iframe.setAttribute('src','http://www.1sucai.cn');
}