http://stackoverflow.com/questions/2803/how-do-you-find-out-the-caller-function-in-javascript
arguments.callee.caller.toString()
注意：对
var kkk = { aaa: function(){ mmm(); }};
var mmm = function(){ alert(arguments.callee.caller == kkk.aaa) };
kkk.aaa()
这样的方法, toString()取不到方法名，只会把方法体打印出来。但是,arguments.callee.caller == kkk.aaa会返回true.