Js 錯誤：“Uncaught (in promise) SyntaxError: Unexpected end of input”

Question

我遇到了錯誤： Uncaught (in promise) SyntaxError: Unexpected end of input on try to post refs to my specific express server,你們能幫我嗎？

function create() {

    event.preventDefault()

    firstName = document.getElementById('firstName').value
    lastName = document.getElementById('lastName').value
    username = document.getElementById('username').value
    password = document.getElementById('password').value

    const userInfo = {
        firstName: firstName,
        lastName: lastName,
        username: username, 
        password: password
    }

    const config = {
        method: "POST",
        mode: "no-cors",
        body: {userInfo},
        headers: {
            "Content-Type":"application/json"
        }
    }

    fetch('https://marcelochat.herokuapp.com/create', config)
    .then(res => res.json())
    .then(resp => {
        console.log(resp)
    })
}

錯誤在這里： .then(res => res.json())注意：firstName、lastName、用戶名和密碼常量是輸入值

Answer 1

    firstName = document.getElementById('firstName').value
    lastName = document.getElementById('lastName').value
    username = document.getElementById('username').value
    password = document.getElementById('password').value

這個變量是否超出范圍？

如果沒有，試試這個

  let  firstName = document.getElementById('firstName').value
  let  lastName = document.getElementById('lastName').value
  let  username = document.getElementById('username').value
  let  password = document.getElementById('password').value

並且 config.body userInfo 應該在對象內部嗎？