<script type="text/javascript">
       function YY(data) {
                execScript(data);
                    alert(data);
                }
                function CompleteDo() {
                    alert("complete!");
                    message();
                }
        function testeval() {
            //eval("id=1");
            $.ajax({
                url: "test.js",
                success: function(data) { YY(data); },
                error: function(XMLHttpRequest, textStatus, errorThrown) { alert(XMLHttpRequest + textStatus + errorThrown); },
                complete: function() { CompleteDo(); }
            });
            //execScript("alert('aaa')");
            //alert(id);
        }
        if (typeof (message) == 'undefined') {
            alert("未定义");
            testeval();
        }
        else {
            message();
        }
       
      
        //execScript("message()");
        //alert(id);
    </script>

test.js的文件

var TestClass=function message() {
alert('aaa');

}