multipart/form-data possible to send with javascript?

Question

I am sending a file over POST together with text "name" using this form:

<form enctype="multipart/form-data" action="https://site[DOT]net/upload" method="post">
  <input id="name" type="text" />
  <input id="data" type="file" />
  <button type="submit" name="submit" />
</form>

I would like to do the exect same using javascript. In addition I dont want to be redirected. I want to stay on the html page and just show a popup "Upload done". How can I do this in javascript (no jquery)?

EDIT:

I tried this code but the POST is not working:

<script>
function uploader {
  var formData = new FormData();
  formData.append("name", "Smith");
  formData.append("data", fileInputElement.files[0]);
  var request = new XMLHttpRequest();

  request.open("POST", "https://site[DOT]net/upload");
  request.send(formData);
}
</script>

<form>
    <input id="name" type="text" />
    <input id="data" type="file" />
    <button type="submit" name="submit" />
    <button onclick="uploader()">Click</button>
</form>

Answer 1

Uploading the entire form with javascript, including the files, can be done by using the FormData API and XMLHttpRequest

var form = document.getElementById('myForm'); // give the form an ID
var xhr  = new XMLHttpRequest();              // create XMLHttpRequest
var data = new FormData(form);                // create formData object


xhr.onload = function() {
    console.log(this.responseText); // whatever the server returns
}

xhr.open("post", form.action);      // open connection
xhr.send(data);                     // send data

If you need to support IE10 and below, it gets increasingly complicated, and would in some cases require posting through iFrames etc.

Answer 2

In case any wants to do this with the new form instead of xhr this is the equivalent. Also see: fetch post with multipart form data

 var form = document.getElementById('formid'); form.onsubmit = async (e) => { e.preventDefault(); const form = e.currentTarget; const url = form.action; try { const formData = new FormData(form); const response = await fetch(url, { method: 'POST', body: formData }); console.log(response); } catch (error) { console.error(error); } }

 <form id="formid" enctype="multipart/form-data" action="#" method="post"> <input id="name" type="text" /> <input id="data" type="file" /> <button type="submit" name="submit">Submint</button> </form>