问无法使用javascript将http POST请求发送到ASP.NET web api控制器

EN

    public class PlayerController : ApiController
{
      public IEnumerable<string> Get()
    {
        return new string[] { "value1", "value2" };
    }

    public string Post(string value)
    {
        return value;
    }
}

 var app = require('express')();
var http = require('http').Server(app);
var XMLHttpRequest = require("xmlhttprequest").XMLHttpRequest;
var xhr = new XMLHttpRequest();
var querystring = require('querystring');
var io = require('socket.io')(http);
io.on('connection', function (socket) {
    console.log('A user connected ' + socket.handshake.address);
    PostRequest(socket.handshake.address);
    //Whenever someone disconnects this piece of code executed
    socket.on('disconnect', function () {
        console.log('A user disconnected ' + socket.handshake.address);
    });
});


function PostRequest(data) {

    var url = "http://localhost:4928/api/Player";
    var params = "value=" + data;/* querystring.stringify({ "value": data })*/
    xhr.open('POST', url, true);
    xhr.onreadystatechange = function () {//Call a function when the state changes.
        if (xhr.readyState == 4 && xhr.status == 200) {
            console.log(xhr.responseText);
        }
        console.log(xhr.responseText);

    }
    xhr.send(querystring.stringify({ value: "sss" }));

}


http.listen(3000, function () {
    console.log('listening on *:3000');
});