如何将ajax post数据传递到nodejs服务器？

var xhr = new XMLHttpRequest();
xhr.open("POST", "/api/data", true);
xhr.setRequestHeader("Content-Type", "application/json");
xhr.onreadystatechange = function() {
  if (xhr.readyState === 4 && xhr.status === 200) {
    // 请求成功后的处理逻辑
    console.log(xhr.responseText);
  }
};
var data = { key: "value" }; // 要发送的数据
xhr.send(JSON.stringify(data));

npm install express body-parser

const express = require("express");
const bodyParser = require("body-parser");

const app = express();
app.use(bodyParser.json());

app.post("/api/data", (req, res) => {
  const data = req.body; // 获取POST请求中的数据
  // 处理数据的逻辑
  console.log(data);
  res.send("Data received"); // 返回响应
});

app.listen(3000, () => {
  console.log("Server started on port 3000");
});