reverse a singly-linked list

reverse_list.js

var d = {id:'d', next:null};
var c = {id:'c', next:d};
var b = {id:'b', next:c};
var a = {id:'a', next:b};

function reverse( list ) {
    var head = list.next;
    var tail = list;
    var next;
    tail.next = null;
    while ( head ) {
        next = head.next;
        head.next = tail;
        tail = head;
        head = next;
    }
    return tail;
}

reverse( a );