JavaScript链表指针问题？

Question

源自一个问题：输入两个单调递增的链表，输出两个链表合成后的链表，当然我们需要合成后的链表满足单调不减规则。解决代码：/*function ListNode(x){    this.val = x;    this.next = null;}*/function Merge(pHead1, pHead2){    if(!pHead1){        return pHead2 ? pHead2 : null    } else if(!pHead2){        return pHead1;    }    // debugger;    var curr1 = pHead1;    var curr2 = pHead2;    var result = new ListNode(-1);    var curr = result;    while(curr1 && curr2){        if(curr1.val < curr2.val){            curr.next = curr1;            curr1 = curr1.next;        } else{            curr.next = curr2;            curr2 = curr2.next;        }        curr = curr.next;    }    if(curr1){        curr.next = curr1;    }    if(curr2){        curr.next = curr2;    }    //防止内存泄露    curr = result.next;    result.next = null;    result = curr;    curr = curr1 = curr2 = null;    return result;}这个防止内存泄露的代码没有看懂curr = result.next之后curr是指向了result.next的地址吧，还是复制了一份？引用类型因该是指向地址吧？那么result.next = null之后curr也变成null了吧？？为什么还可以result=curr，最后返回result