如何使用js实现点赞

<div id="like-section">
  <button id="like-button">点赞</button>
  <span id="like-count">0</span>
</div>

document.addEventListener('DOMContentLoaded', function() {
  const likeButton = document.getElementById('like-button');
  const likeCount = document.getElementById('like-count');
  let isLiked = false; // 初始状态为未点赞

  likeButton.addEventListener('click', function() {
    if (isLiked) {
      // 如果已经点赞，则取消点赞
      isLiked = false;
      likeCount.textContent = parseInt(likeCount.textContent) - 1;
    } else {
      // 如果未点赞，则进行点赞
      isLiked = true;
      likeCount.textContent = parseInt(likeCount.textContent) + 1;
    }

    // 同步点赞状态到服务器（这里使用fetch API作为示例）
    fetch('/api/like', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({ liked: isLiked })
    }).then(response => response.json())
      .then(data => {
        console.log('Success:', data);
      })
      .catch((error) => {
        console.error('Error:', error);
      });
  });
});

const express = require('express');
const app = express();
app.use(express.json());

let likeCount = 0;

app.post('/api/like', (req, res) => {
  if (req.body.liked) {
    likeCount += 1;
  } else {
    likeCount -= 1;
  }
  res.json({ message: 'Like status updated', count: likeCount });
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});