The XMLHttpRequestResponseType type is an enumerated set of strings which are used to specify the type of data contained in the response of an XMLHttpRequest. These values are used when getting or setting the responseType on the request.
An empty responseType string is treated the same as "text", the default type (therefore, as a DOMString.
Similar to "arraybuffer", but the data is received in a stream. When using this response type, the value in response is only available in the handler for the progress event, and only contains the data received since the last progress event, rather than the cumulative data received since the request was sent.
Accessing response during a progress event returns the data received so far. Outside the progress event handler, the value of response is always null.
The response is part of a streaming download; this response type is only allowed for download requests, and is only supported by Internet Explorer.