<script type="text/javascript">
function getCurrentScriptPath() {
 //firefox可以直接得到currentScript
 if (document.hasOwnProperty('currentScript')) {
   return document.currentScript.src;
 }
 var scripts = document.scripts || document.getElementsByTagName('script'),
   len = scripts.length,
   state = 'interactive';
 //兼容IE
 for (var i=0; i <len; i++) {
   if (scripts[i].readyState==state) {
     return scripts[i].src;
   }
 }
 //webkit
 return scripts[len-1].src;
}
</script>

document.write('<script src="a.a.js"><\/script>');
document.write('<script src="a.b.js"><\/script>');

var scripts = document.getElementsByTagName('script');
document.title = script[script.length-1].src;
//如果是a.a.js理解起来还很容易 - script阻塞加载嘛
//此时这里IE输出是a.b.js，其他浏览器是a.a.js。