The error event is fired when the request encountered an error.

Use the event name in methods like addEventListener(), or set an event handler property.

addEventListener("error", (event) => {});

onerror = (event) => {};

A ProgressEvent. Inherits from Event.

In addition to the properties listed below, properties from the parent interface, Event, are available.

lengthComputable Read only

A boolean flag indicating if the total work to be done, and the amount of work already done, by the underlying process is calculable. In other words, it tells if the progress is measurable or not.

loaded Read only

A 64-bit unsigned integer value indicating the amount of work already performed by the underlying process. The ratio of work done can be calculated by dividing total by the value of this property. When downloading a resource using HTTP, this only counts the body of the HTTP message, and doesn't include headers and other overhead.

total Read only

A 64-bit unsigned integer representing the total amount of work that the underlying process is in the progress of performing. When downloading a resource using HTTP, this is the Content-Length (the size of the body of the message), and doesn't include the headers and other overhead.

You can use the error event to detect a problem with the upload. For a complete code example that uploads a file and displays a progress bar, see the main XMLHttpRequestUpload page.

// In case of an error we hide the progress bar
// Note that this event 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);

• Related events: loadstart, load, progress, abort, loadend, timeout
• XMLHttpRequestUpload