Ajax响应不是来自node.js

Question

My Ajax request is not receiving proper response! It always enters readyState '4' with response status '0' ??

Client Code:

var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function(){
                    if(xhttp.readyState == 4 && xhttp.status == 200){
                        document.getElementById("lastNameLabel").innerHTML = "response recieved!"; 
                        const responseJSON = JSON.parse(xhttp.responseText);
                        if(responseJSON.emailTaken == "false"){
                            window.location = server+"/client/home.html";
                        }
                    }
                };
xhttp.open("POST", server+"/signUp", true);
xhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
xhttp.send("email="+email);

server Code (Node.js + Express):

app.post('/signUp', (req, res) => {
    res.end("it worked!!");
});

I Know my Server is processing the request since I see the url call, but the response never reaches the html client!!. I'm Super Stuck!

Answer 1

Putting @jaromanda-x's suggestion as an answer, you need to enable CORS in your server.

This is how it's done:

var cors = require('cors');

app.use(cors());

For more info, refer this express doc about it.

Answer 2

您必须让NodeJS服务器使用HTTP响应消息进行回复，该HTTP响应消息包括状态码和原因短语，例如

res.status(200).send({ status: 'ok' });