Ajaxian » Sandboxing JavaScript with iframes

// create an <iframe>
var iframe = document.createElement("iframe");
iframe.style.display = "none";
document.body.appendChild(iframe);
 
// write a script into the </iframe><iframe> and create the sandbox
frames[frames.length - 1].document.write(
        "<script>"+
        "var MSIE/*@cc_on =1@*/;"+ // sniff
        "parent.sandbox=MSIE?this:{eval:function(s){return eval(s)}}"+
        "<\/script>"
);