我从快递中得到未定义。 为什么 req.body 显示空的 object {}？

Question

This is noob question but I am new to it. Req.body is undefined. I tried without body-

parser and with body-parser, I keep getting the same result I tried all solutions

available in StackOverflow but I keep getting the same result

    <script>
        document.addEventListener("DOMContentLoaded", () => {
            document.getElementById('send').addEventListener('click', (e) => {
                var message = { name: document.getElementById('name').value, message: document.getElementById('message').value }
                postMessages(message)
            })
            getMessages()

        });
        function addMessages(message) {
            const ele = document.getElementById('messages')
            const h4 = document.createElement('h4')
            const p = document.createElement('p')
            h4.textContent = `${message.name}`
            p.textContent = `${message.message}`
            ele.append(h4, p)
        }
        function postMessages(message) {
            const Url = "http://localhost:3000/messages"
            fetch(Url, {
                method: 'POST',
                body: message,
            })
        }
    </script>
</body>
</html>
var express = require('express')
var bodyParser = require('body-parser')
var app = express()

app.use(express.static(__dirname))
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({ extended: false }))
var messages = [
    { name: "Tim", message: "Hi" },
    { name: "Jane", message: "Hello" }
]
app.post('/messages', (req, res) => {
    console.log(req.body)
    messages.push(req.body)
    res.sendStatus(200)
})

Answer 1

You need to change your fetch function and first JSON.strindify your message and then add correct headers:

function postMessages(message) {
        const Url = "http://localhost:3000/messages"
        fetch(Url, {
            method: 'POST',
            headers: {'Content-Type': 'application/json'},
            body: JSON.stringify(message),
        })
    }