In an AJAX transaction, which readyState value indicates that the XMLHttpRequest has been sent but no response has been received yet?

In an AJAX transaction, the appropriate readyState value that signifies the XMLHttpRequest has been sent but no response has been received yet is represented by the value 3.

At this stage (readyState value 3), the request has been established, and the client is in the process of receiving the response from the server. Specifically, this indicates that the server has started to respond, but the complete response has not yet been received. The client can potentially start accessing some response headers, but the body of the response is not available at this point.

Understanding the sequence of readyState values is crucial because it helps in managing the flow of data and operations in asynchronous requests. The transitions occur as follows: readyState 0 is when the request has not yet been initialized, readyState 1 is when the connection to the server has been established, readyState 2 indicates that the request has been received, and readyState 3 signals that the request is in process and some data may be arriving. It's at this point (readyState 3) that the application can potentially progress in handling incoming data while awaiting the completion of the transaction.