[javascript] FormData.append ( “key”, “value”)가 작동하지 않습니다.

이것에 무엇이 잘못되었는지 말해 줄 수 있습니까?

var formdata = new FormData();
formdata.append("key", "value");
console.log(formdata);

내 출력은 다음과 같습니다. “키”- “값”쌍을 찾을 수 없습니다.

FormData
*__proto__: FormData
**append: function append() { [native code] }
***arguments: null
***caller: null
***length: 0
***name: "append"
***prototype: append
***__proto__: function Empty() {}
*constructor: function FormData() { [native code] }
**arguments: null
**caller: null
**length: 0
**name: "FormData"
**prototype: FormData
**toString: function toString() { [native code] }
*__proto__: Object
**__proto__: Object
**__defineGetter__: function __defineGetter__() { [native code] }
**__defineSetter__: function __defineSetter__() { [native code] }
**__lookupGetter__: function __lookupGetter__() { [native code] }
**__lookupSetter__: function __lookupSetter__() { [native code] }
**constructor: function Object() { [native code] }
**hasOwnProperty: function hasOwnProperty() { [native code] }
**isPrototypeOf: function isPrototypeOf() { [native code] }
**propertyIsEnumerable: function propertyIsEnumerable() { [native code] }
**toLocaleString: function toLocaleString() { [native code] }
**toString: function toString() { [native code] }
**valueOf: function valueOf() { [native code] }

이해할 수 없습니다! 어제는 너무 잘 작동했고 오늘은 내 머리가 키보드를 너무 많이 추락했습니다! Firefox, Chrome, 둘 다 동일 : /

답변

var xhr = new XMLHttpRequest;
xhr.open('POST', '/', true);
xhr.send(data);

$('form').submit(function(){
    var sessionID = 8;
    var formData = new FormData(this);
    formData.append('id', sessionID);

    $.ajax({
        url: "yoururl.php",
        data: formData,
        processData: false,
        contentType: false,
        type: 'POST',
        success: function(data){
            alert(data);
        }
    });
});

$sessionID = $_POST['id'];
$files = $_FILES['image'];

$foreach ($files as $key=>val){
    //...
}

for (var data of formData) {
  console.log(data);
}

  const formData = new FormData(this.form);
  for (const [key, value] of formData.entries()) {
      formObject[key] = value;
  }

import React from 'react';
import formDataToObject from 'form-data-to-object';

  ...

let formObject = {};

// EDGE compatibility -  replace FormData by
for (let i = 0; i < this.form.length; i++) {
  if (this.form[i].name) {
    formObject[this.form[i].name] = this.form[i].value;
  }
}

const data = formDataToObject.toObj(formObject): // convert "user[email]":"customer@mail.com" => "user":{"email":"customer@mail.com"}

const orderRes = await fetch(`/api/orders`, {
        method: 'POST',
        credentials: 'same-origin',
        headers: {
          'Content-Type': 'application/json'
        },
        body: JSON.stringify(data)
      });

const order = await orderRes.json();