为什么JavaScript Array Loop打印额外的线？

Question

以下应该打印4个名字，如下：

alice

bob

michelle

timmy

代码：

function Person (name, age) {
    this.name = name;
    this.age = age;
}

family = new Array();
family[0] = new Person ("alice", 40);
family[1] = new Person ("bob", 42);
family[2] = new Person ("michelle", 8);
family[3] = new Person ("timmy", 6);


for (var i = 0; i< family.length; i++) {
    console.log(family[i].name);
}

这样做但它也打印了第5行：

alice

bob

michelle

timmy

alicebobmichelletimmy

这是什么原因？