XMLHttpRequest: readyState property

{{APIRef("XMLHttpRequest API")}} {{AvailableInWorkers("window_and_worker_except_service")}}

The XMLHttpRequest.readyState property returns the state an XMLHttpRequest client is in. An XHR client exists in one of the following states:

• UNSENT
  • : The XMLHttpRequest client has been created, but the open() method hasn't been called yet.
• OPENED
  • : open() method has been invoked. During this state, the request headers can be set using the setRequestHeader() method and the send() method can be called which will initiate the fetch.
• HEADERS_RECEIVED
  • : send() has been called, all redirects (if any) have been followed and the response headers have been received.
• LOADING
  • : Response's body is being received. If responseType is "text" or empty string, responseText will have the partial text response as it loads.
• DONE
  • : The fetch operation is complete. This could mean that either the data transfer has been completed successfully or failed.

Example

const xhr = new XMLHttpRequest();
console.log("UNSENT", xhr.readyState); // readyState will be 0

xhr.open("GET", "/api", true);
console.log("OPENED", xhr.readyState); // readyState will be 1

xhr.onprogress = () => {
  console.log("LOADING", xhr.readyState); // readyState will be 3
};

xhr.onload = () => {
  console.log("DONE", xhr.readyState); // readyState will be 4
};

xhr.send(null);

Specifications

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Browser compatibility

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