反应不使用代理URL将数据发布到服务器

Question

对于前端，我在React JS中有一个代码，并且正在尝试将JSON数据作为React到Express的查询。 Express Server正在端口5000

  const [ search, setSearch ] = useState("");

  const updatesearches = async () => {
    const result = await fetch("/api/searchposts",{
      method: "POST",
      body: JSON.stringify({search}),
      headers: {
        "Content-Type" : "application/json",
      }
    });
    const res = await result.json();
    console.log(res);
  }

  useEffect(() => {
    updatesearches();
  },[search])

服务器运行完美，我已经在邮递员上测试过。对于后端，这里是exrpess控制器的代码：

const { PostModel }  = require("../models");

const getsearchposts = async (req , res) => {
    const result = await PostModel.find({title : "Ukraine war: Gruesome evidence points to war crimes on road outside Kyiv"});
    res.send(result);
}
module.exports = { getsearchposts };

在poststrouters.js文件中

const express = require("express");
const router = express.Router();
const { getsearchposts } = require("../controllers/getsearchposts");

router.post("/api/searchposts", getsearchposts );

module.exports = router;

，在react package.json文件中，我使用了“ proxy”：“ http：// local -host ：5000“，

当我更改搜索状态在下面

POST http://localhost:3000/api/searchposts net::ERR_INTERNET_DISCONNECTED
Sidebar.js:9          Uncaught (in promise) TypeError: Failed to fetch
    at updatesearches (Sidebar.js:9:1)
    at Sidebar.js:22:1
    at invokePassiveEffectCreate (react-dom.development.js:23479:1)
    at HTMLUnknownElement.callCallback (react-dom.development.js:3945:1)
    at Object.invokeGuardedCallbackDev (react-dom.development.js:3994:1)
    at invokeGuardedCallback (react-dom.development.js:4056:1)
    at flushPassiveEffectsImpl (react-dom.development.js:23566:1)
    at unstable_runWithPriority (scheduler.development.js:468:1)
    at runWithPriority$1 (react-dom.development.js:11268:1)
    at flushPassiveEffects (react-dom.development.js:23439:1)