为什么下面的post没问题，但是put请求会报错：

XMLHttpRequest cannot load http://localhost:8001/service. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:63343' is therefore not allowed access.

客户端

$.ajax({

url: 'http://localhost:8001/man',

method: 'POST',

success: function (data) {

console.log(data)

}

});

$.ajax({

url: 'http://localhost:8001/service',

method: 'PUT',

success: function (data) {

console.log(data)

}

});

服务端

app.post('/man', function (req, res) {

var body = req.body;

console.log(body);

if (body) {

res.header("Content-Type", "application/json; charset=utf-8");

res.header("Access-Control-Allow-Origin", "*");

res.header("Access-Control-Allow-Methods", "GET, POST, PATCH, PUT, DELETE, OPTIONS");

res.send(body);

}

});

app.put('/service', function (req, res) {

res.header("Content-Type", "application/json; charset=utf-8");

res.header("Access-Control-Allow-Origin", "*");

res.header("Access-Control-Allow-Methods", "GET, POST, PATCH, PUT, DELETE, OPTIONS");

res.send(req.body);

});