FormData() object is empty in console during POST

Question

this question has been asked before but I couldn't find the answer in another question. when I log my formdata I just get {} i am sending two items that are text and one image file from my client html using fetch

my form

 <form id="addform">

      <div class="form-group">
        <label for="exampleInputPassword1">post</label>
        <input type="text" class="form-control" id="title" placeholder="article title">
        <textarea type="text" class="form-control bigbox" id="body" placeholder=""></textarea>

        <input type="file" id="image" placeholder="image" name="imageFile">
      </div>

      <button id="addpost" type="submit"class="btn btn-primary">add Post</button>
    </form>

postdata function

 async function postData(url = '', data) {

  // Default options are marked with *
  const response = await fetch(url, {
    method: 'POST', // *GET, POST, PUT, DELETE, etc.
    mode: 'no-cors', // no-cors, *cors, same-origin
    cache: 'no-cache', // *default , no-cache, reload, force-cache, only-if-cached
    credentials: 'same-origin', // include, *same-origin, omit
    headers: {
      //'Content-Type': 'application/json'
      'Content-Type': 'application/x-www-form-urlencoded'
    },
    redirect: 'follow', // manual, *follow, error
    referrerPolicy: 'no-referrer', // no-referrer, *no-referrer-when-downgrade, origin, origin-when-cross-origin, same-origin, strict-origin, strict-origin-when-cross-origin, unsafe-url
    body: JSON.stringify(data) // body data type must match "Content-Type" header
  });
  return response.json(); // parses JSON response into native JavaScript objects
}

sending the request with a form object

document.getElementById("addpost").addEventListener('click',function(e){
      e.preventDefault()
      let form = document.getElementById('addform')
      let formdata = new FormData(form)
      formdata.append('title',document.getElementById("title").value)
      formdata.append('body',document.getElementById("body").value)
      formdata.append('imageFile',document.getElementById("image").files[0])    

      postData(`http://${window.location.hostname}:3000/admin/addpost`,formdata)
      .then((data)=>{console.log(data.data)})
    })

what i get in my XHR preview in chrome

{}

I'm not sure why this is happening it just seems to not be grabbing the form values at all

You're not logging your `FormData` anywhere and even then, why would you. If you want to do debugging, use your browser's debugger. The only `console.log()` line in your code above is `console.log(data.data)` and since you've set `mode: 'no-cors'`, you won't be able to read any response data — Phil, May 29 '20 at 00:28
Does this answer your question? [Trying to use fetch and pass in mode: no-cors](https://stackoverflow.com/questions/43262121/trying-to-use-fetch-and-pass-in-mode-no-cors) — Phil, May 29 '20 at 00:32
@Phil no-cors should block the front end to access the response, it shouldn't block the request's content. And OP talked about the Network console, not the js one. — Kaiido, May 29 '20 at 00:46

Kaiido · Accepted Answer · 2020-05-29T00:44:22.217

Don't stringify your FormData, send it directly, and don't set the request headers, let the browser handle that too:

  const response = await fetch(url, {
    method: 'POST', // *GET, POST, PUT, DELETE, etc.
    mode: 'no-cors', // you probably don't want this... let the default "cors"
    cache: 'no-cache', // not sure why you'd want that either...
    credentials: 'same-origin', // include, *same-origin, omit
// removed the Headers, the browser knows how to talk to a server, that's hos job.
    redirect: 'follow', // manual, *follow, error
    referrerPolicy: 'no-referrer', // no-referrer, *no-referrer-when-downgrade, origin, origin-when-cross-origin, same-origin, strict-origin, strict-origin-when-cross-origin, unsafe-url
    body: data // pass directly the FormData here
  });

And note that you don't have to, and probably even shouldn't set all the options of the fetch, just use the defaults, in 99% of cases that's what you need.

@monsterpiece the `body: JSON.stringify(data)` part was the biggest problem. — Kaiido, May 29 '20 at 01:18

FormData() object is empty in console during POST

1 Answers1