怎么判断IE浏览器之类的呢？

Question

我看到有些代码上有这个话-。- 用这句话就好了？
<!--[if lt IE 9]>

<script>

    var e = "abbr, article, aside, audio, canvas, datalist, details, dialog, eventsource, figure, footer, header, hgroup, mark, menu, meter, nav, output, progress, section, time, video, dh-dialog, dh-checkbox".split(', ');

     var i= e.length;while (i--){document.createElement(e[i])}

</script>

<![endif]-->