获得函数的父函数,困扰已久的问题

<script>
function my(){
    this.a=function(){
        document.write("<input onclick='"+this.owner+".c()'>");
        alert(document.body.outerHTML);
        }
    eval(this.owner + "=this");
    this.c=function(){
        event.srcElement.value="123";
        }
    }
var o=new my();
o.a();
</script>