我使用nodejs express服务器。 尽管允许主机，我仍然有一个CORS错误

“请求得资源上不存在”Access-Control-Allow-Origin“标头。”

但仅适用于POSTendpoint。 “得到”没有问题。 我的客户端浏览器允许使用（GET和POST）终结点:

我的服务器:（在http://serverurl上运行）

var whitelist = ['http://localhost:4200', 'http://someOtherDeployUrl.com']
var corsOptionsDelegate = function (req, callback) {
    var corsOptions;
    if (whitelist.indexOf(req.header('Origin')) !== -1) {
        corsOptions = {origin: true} // reflect (enable) the requested origin in the CORS response
    } else {
        corsOptions = {origin: false} // disable CORS for this request
    }
    corsOptions.methods= "GET,HEAD,PUT,PATCH,POST,DELETE"; 
    callback(null, corsOptions) // callback expects two parameters: error and options
}


router.post('/score', cors(corsOptionsDelegate), function (req, res, next) {
    ...
    res.status(200).send('Ok');
});

router.get('/scores', cors(corsOptionsDelegate), function (req, res, next) {
    res.status(200).send(scores);
});

客户端（angular 9）:（在localhost:4200上运行）

  public saveScore(player, score) {
    console.log("save score")
    let objectObservable = this.http.post("http://serverURL/score", {
      player: player,
      score
    }).subscribe(
      data => console.log('success', data),
      error => console.log('oops', error)
    );

    return objectObservable

  }

  public getScores() {
    return this.http.get("http://serverURL/scores");
  }

知道为什么不起作用吗？

GET:

回应:

Referrer Policy: no-referrer-when-downgrade
Access-Control-Allow-Origin: http://localhost:4200
Content-Length: 2
Content-Type: application/json; charset=utf-8
Date: Sun, 14 Jun 2020 14:42:35 GMT
Etag: W/"2-l9Fw4VUO7kr8CvBlt4zaMCqXZ0w"
Server: Cowboy
Vary: Origin
Via: 1.1 vegur
X-Powered-By: Express

请求:

Accept: application/json, text/plain, */*
Accept-Encoding: gzip, deflate
Accept-Language: en,en-US;q=0.9,fr-FR;q=0.8,fr;q=0.7
Connection: keep-alive
DNT: 1
Host: serverUrl
If-None-Match: W/"2-l9Fw4VUO7kr8CvBlt4zaMCqXZ0w"
Origin: http://localhost:4200
Referer: http://localhost:4200/menu
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36

（失败的）POST响应的整个响应/请求:

Allow: POST
Connection: keep-alive
Content-Length: 4
Content-Type: text/html; charset=utf-8
Date: Sun, 14 Jun 2020 14:30:00 GMT
Etag: W/"4-Yf+Bwwqjx254r+pisuO9HfpJ6FQ"
Server: Cowboy
Via: 1.1 vegur
X-Powered-By: Express

请求:

Accept: */*
Accept-Encoding: gzip, deflate
Accept-Language: en,en-US;q=0.9,fr-FR;q=0.8,fr;q=0.7
Access-Control-Request-Headers: content-type
Access-Control-Request-Method: POST
Connection: keep-alive
Host: serverUrl
Origin: http://localhost:4200
Referer: http://localhost:4200/menu
Sec-Fetch-Mode: cors
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36