JavaScript链表

普通链表，代码参考自Java，按需自行调整

 function LinkedList(s) {
            var size = s||5, cnt = 0;
            var first, last;

            return {
              add: function (v) {
                var e = {value: v, pre:last};
                if(cnt === 0){last = first = e; cnt ++;}
                else if(cnt === size){first = first.next; last.next = e; last = e;}
                else {cnt++; last.next = e; last = e;}
              },
              lastNode: function(){
                return last;
              },
              firstNode: function(){
                return first;
              },
              get: function (idx) {
                var v;
                while(idx --> 0){
                  v = first.next
                }
                return v.value;
              },
              first: function () {
                return first.value;
              },
              last: function () {
                return last.value;
              },
              peek: function () {
                var res = last;
                last = last.pre;
                delete last.next;
                return res;
              }
            }
          }

扩展了一部分功能，用于做播放器，上一首、下一首、最后一首、第一首这样的功能

/**
             * 简单的链表
             */
            function LinkedList(s) {
              var size = s||5, cnt = 0;
              var first, last, cur;

              return {
                add: function (v) {
                  var e = {value: v, pre:last};
                  if(cnt === 0){last = first = e; cnt ++;}
                  else if(cnt === size){first = first.next; delete first.pre; last.next = e; last = e;}
                  else {cnt++; last.next = e; last = e;}
                },
                lastNode: function(){
                  return last;
                },
                firstNode: function(){
                  return first;
                },
                get: function (idx) {
                  var n = first;
                  while(idx --> 0){
                    n = n.next
                  }
                  return n.value;
                },
                set: function (idx, value) {
                  var n = first, id = idx;
                  while(id --> 0){
                    n = n.next
                  }
                  cnt = idx + 1;
                  n.value = value;
                  last = n;
                },
                first: function () {
                  cnt = 1;
                  last = first;
                  return first.value;
                },
                last: function () {
                  while (last.next){
                    last = last.next;
                    cnt++;
                  }
                  return last.value;
                },
                next: function(){
                  if(last.next){
                    cnt++;
                    last = last.next;
                    return last.value;
                  }
                },
                back: function(){
                  if(last.pre){
                    cnt--;
                    last = last.pre;
                    return last.value;
                  }
                }
              }
            }