[html5] XHR Questions

Gomer Thomas gomer at gomert-consulting.com
Tue Mar 15 15:58:35 PDT 2016

I have several questions about the XMLHttpRequest specification.

(1)    As far as I can tell, if the response is of type "text", then a
partial response can be accessed during the transmission of the response.
However, if the response is of any other type, then the response cannot be
accessed until the transmission is finished. Why is that so? I have an
application for which it is important to access partial responses while the
transmission is in progress for a "blob" response (actually an ISO BMFF

(2)    The specification talks about the "response's body's transmitted" and
the "response's body's length". What do these mean? I cannot find any
definition of them in the standard. Is the "response's body's transmitted"
the number of bytes that have been transmitted so far? Is the "response's
body's length" the total length of the response in bytes? It would be good
to define these terms in the specifications. 

(3)    After reading the relevant part of the specification three times, I
am still confused about what causes an "onprogress" event to be fired. In
particular is a "progress" event named "progress" fired at regular intervals
during transmission of a response, or whenever additional bytes arrive for a
response, or what? I would find the first of these useful if my app was
tracking the progress of a response for display to a human user. I would
find the second of these useful if I was able to access partial responses
and wanted to know when there is something new to access.  

Regards, Gomer Thomas


Gomer Thomas Consulting, LLC

9810 132nd St NE

Arlington, WA 98223

Cell: 425-309-9933


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