下面这段代码有错误吗?为什么在浏览器显示的是空白页面
<script type="text/javascript">function member(name,gender)
{
this.name=name;
this.gender=gender;
}
function showproperty(obj,objstring)
{
var str="";
for(var i in obj)
{
str+=objString+"."+i+"="+obj[i]+"<br>";
}
return str;
}
person1=new member("zhangsan","男");
person2=new member("lisi","女");
document.write(showproperty(person1,"person"));
document.write(showproperty(person2,"person"));
</script>