XMLHttpRequestUpload

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

Note: This feature is available in Web Workers, except for Service Workers.

The XMLHttpRequestUpload interface represents the upload process for a specific XMLHttpRequest. It is an opaque object that represents the underlying, browser-dependent, upload process. It is an XMLHttpRequestEventTarget and can be obtained by calling XMLHttpRequest.upload.

EventTarget XMLHttpRequestEventTarget XMLHttpRequestUpload

Instance properties

This interface has no specific property, but inherits the properties of XMLHttpRequestEventTarget and of EventTarget.

Instance methods

This interface has no specific method, but inherits the methods of XMLHttpRequestEventTarget and of EventTarget.

Events

This interface has no specific event, but inherits the events of XMLHttpRequestEventTarget.

Examples

Uploading a file with a timeout

This allows you to upload a file to a server; it displays a progress bar while the upload is happening as well as a message with the progress and the results, success or failure. An abort button allows to stop an upload.

HTML

html
<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width" />
    <title>XMLHttpRequestUpload test</title>
    <link rel="stylesheet" href="xhrupload_test.css" />
    <script src="xhrupload_test.js"></script>
  </head>
  <body>
    <main>
      <h1>Upload a file</h1>
      <p>
        <label for="file">File to upload</label><input type="file" id="file" />
      </p>
      <p>
        <progress></progress>
      </p>
      <p>
        <output></output>
      </p>
      <p>
        <button disabled id="abort">Abort</button>
      </p>
    </main>
  </body>
</html>

CSS

css
body {
  background-color: lightblue;
}

main {
  margin: 50px auto;
  text-align: center;
}

#file {
  display: none;
}

label[for="file"] {
  background-color: lightgrey;
  padding: 10px;
}

progress {
  display: none;
}

progress.visible {
  display: inline;
}

JavaScript

js
const fileInput = document.getElementById("file");
const progressBar = document.querySelector("progress");
const log = document.querySelector("output");
const abortButton = document.getElementById("abort");

fileInput.addEventListener("change", () => {
  const xhr = new XMLHttpRequest();
  xhr.timeout = 2000; // 2 seconds

  // Link abort button
  abortButton.addEventListener(
    "click",
    () => {
      xhr.abort();
    },
    { once: true },
  );

  // When the upload starts, we display the progress bar
  xhr.upload.addEventListener("loadstart", (event) => {
    progressBar.classList.add("visible");
    progressBar.value = 0;
    progressBar.max = event.total;
    log.textContent = "Uploading (0%)…";
    abortButton.disabled = false;
  });

  // Each time a progress event is received, we update the bar
  xhr.upload.addEventListener("progress", (event) => {
    progressBar.value = event.loaded;
    log.textContent = `Uploading (${(
      (event.loaded / event.total) *
      100
    ).toFixed(2)}%)…`;
  });

  // When the upload is finished, we hide the progress bar.
  xhr.upload.addEventListener("loadend", (event) => {
    progressBar.classList.remove("visible");
    if (event.loaded !== 0) {
      log.textContent = "Upload finished.";
    }
    abortButton.disabled = true;
  });

  // In case of an error, an abort, or a timeout, we hide the progress bar
  // Note that these events can be listened to on the xhr object too
  function errorAction(event) {
    progressBar.classList.remove("visible");
    log.textContent = `Upload failed: ${event.type}`;
  }
  xhr.upload.addEventListener("error", errorAction);
  xhr.upload.addEventListener("abort", errorAction);
  xhr.upload.addEventListener("timeout", errorAction);

  // Build the payload
  const fileData = new FormData();
  fileData.append("file", fileInput.files[0]);

  // Theoretically, event listeners could be set after the open() call
  // but browsers are buggy here
  xhr.open("POST", "upload_test.php", true);

  // Note that the event listener must be set before sending (as it is a preflighted request)
  xhr.send(fileData);
});