JavaScript单链表详解与实现

  +---+    +---+    +---+
  | A | -> | B | -> | C |
  +---+    +---+    +---+

class Node {
  constructor(value) {
    this.value = value;
    this.next = null; // 初始时，下一个节点为空
  }
}

class LinkedList {
  constructor() {
    this.head = null; // 初始时，链表为空
    this.length = 0; // 初始时，链表长度为 0
  }
  // 在链表末尾添加一个节点
  append(value) {
    const newNode = new Node(value);
    if (!this.head) {
      this.head = newNode;
    } else {
      let current = this.head;
      while (current.next) {
        current = current.next;
      }
      current.next = newNode;
    }
    this.length++;
  }
  // 在指定位置插入一个节点
  insert(position, value) {
    if (position < 0 || position > this.length) {
      return false;
    }
    const newNode = new Node(value);
    if (position === 0) {
      newNode.next = this.head;
      this.head = newNode;
    } else {
      let index = 0;
      let current = this.head;
      let previous = null;
      while (index < position) {
        previous = current;
        current = current.next;
        index++;
      }
      newNode.next = current;
      previous.next = newNode;
    }
    this.length++;
    return true;
  }
  // 根据值查找节点的位置
  indexOf(value) {
    let index = 0;
    let current = this.head;
    while (current) {
      if (current.value === value) {
        return index;
      }
      current = current.next;
      index++;
    }
    return -1; // 未找到
  }
  // 根据位置删除一个节点
  removeAt(position) {
    if (position < 0 || position >= this.length) {
      return null;
    }
    let current = this.head;
    if (position === 0) {
      this.head = current.next;
    } else {
      let index = 0;
      let previous = null;
      while (index < position) {
        previous = current;
        current = current.next;
        index++;
      }
      previous.next = current.next;
    }
    this.length--;
    return current.value;
  }
  // 移除指定值的第一个节点
  remove(value) {
    const position = this.indexOf(value);
    return this.removeAt(position);
  }
  // 返回链表是否为空
  isEmpty() {
    return this.length === 0;
  }
  // 返回链表的长度
  size() {
    return this.length;
  }
  // 返回链表的字符串表示
  toString() {
    let current = this.head;
    let result = '';
    while (current) {
      result += current.value + ' -> ';
      current = current.next;
    }
    return result + 'null';
  }
}

const linkedList = new LinkedList();
// 插入节点到链表末尾
linkedList.append('A');
linkedList.append('B');
linkedList.append('C');
// 链表现在是: A -> B -> C -> null
// 在第二个位置插入新节点
linkedList.insert(1, 'D');
// 链表现在是: A -> D -> B -> C -> null

// 从第一个位置删除节点
linkedList.removeAt(0);
// 链表现在是: D -> B -> C -> null
// 删除包含特定值的节点
linkedList.remove('B');
// 链表现在是: D -> C -> null

const position = linkedList.indexOf('C'); // 查找 'C' 的位置
console.log(position); // 输出 1

console.log(linkedList.toString()); // 输出 'D -> C -> null'
// 遍历链表并输出每个节点的值
let current = linkedList.head;
while (current) {
  console.log(current.value);
  current = current.next;
}