«

I've search far and wide for an answer, so forgive me if this is a
stupid question. (Well, it probably is.)

Consider the following JavaScript:

var foo = new Image();
foo.src = "http://some.server.com/some_filename.gif";

Now, the browser will retrieve 'some_filename.gif' from some.server.com
and put it into the object foo. What I want to do is then subsequently
analyze the actual binary data contained inside some_filename.gif.
(Specifically, I just need to look at the first few bytes.) Is there
any way to do this in just JavaScript?

Thanks in advance for any assistance.

"dirtside" <> wrote in message
news: ups.com...
> I've search far and wide for an answer, so forgive me if this is a
> stupid question. (Well, it probably is.)
>
> Consider the following JavaScript:
>
> var foo = new Image();
> foo.src = "http://some.server.com/some_filename.gif";
>
> Now, the browser will retrieve 'some_filename.gif' from some.server.com
> and put it into the object foo. What I want to do is then subsequently
> analyze the actual binary data contained inside some_filename.gif.
> (Specifically, I just need to look at the first few bytes.) Is there
> any way to do this in just JavaScript?
>
> Thanks in advance for any assistance.
>

Will this help?

function XML() {
var sURL = "http://some.server.com/some_filename.gif";
var oXML = new ActiveXObject("Msxml2.XMLHTTP.3.0");
oXML.open("GET",sURL,false);
oXML.send();
return oXML.responseBody;
}

alert( XML() );


You'll see a bunch of question marks but that's the binary data.
Substituting .responseText will show you some readable text ...


You can test with:
var sURL = "http://www.google.com/intl/en/images/logo.gif";

You might have to use one of these instead:
var oXML = new ActiveXObject("Msxml2.XMLHTTP");
var oXML = new ActiveXObject("Microsoft.XMLHTTP");

On 7 Dec 2005 17:10:37 -0800, in comp.lang.javascript "dirtside"
<> wrote:

>| I've search far and wide for an answer, so forgive me if this is a
>| stupid question. (Well, it probably is.)
>|
>| Consider the following JavaScript:
>|
>| var foo = new Image();
>| foo.src = "http://some.server.com/some_filename.gif";
>|
>| Now, the browser will retrieve 'some_filename.gif' from some.server.com
>| and put it into the object foo. What I want to do is then subsequently
>| analyze the actual binary data contained inside some_filename.gif.
>| (Specifically, I just need to look at the first few bytes.) Is there
>| any way to do this in just JavaScript?
>|
>| Thanks in advance for any assistance.

This is server-side code but you might be able to convert it to
client-side.
http://4guysfromrolla.com/webtech/050300-1.shtml
---------------------------------------------------------------
: Remove your pants to reply
---------------------------------------------------------------

That looks like IE-specific code... whatever I do has to be
cross-platform. (I tried the above code in Mozilla, and was unsurprised
when the JavaScript debugger said it didn't know what 'ActiveXObject'
was ).

"dirtside" <> wrote in message
news: oups.com...
> That looks like IE-specific code... whatever I do has to be
> cross-platform. (I tried the above code in Mozilla, and was unsurprised
> when the JavaScript debugger said it didn't know what 'ActiveXObject'
> was ).
>

Try this.


function getRequestObj() {
var ret = null;
var xml = [
"MSXML2.XMLHTTP.5.0",
"MSXML2.XMLHTTP.4.0",
"MSXML2.XMLHTTP.3.0",
"MSXML2.XMLHTTP",
"Microsoft.XMLHTTP"];
if (window.ActiveXObject) {
for (var i=0; i<xml.length; i++) {
try {
ret = new ActiveXObject(xml[i]);
break;
} catch(e) {}
}
} else if(window.XMLHttpRequest) {
try {
ret = new XMLHttpRequest();
} catch(e) {}
}
return ret;
}

var sURL = "http://some.server.com/some_filename.gif";
var oXML = getRequestObj();
oXML.open("GET",sURL,false);
oXML.send();

// if you want the "GIF89" content prefix
alert(oXML.responseText);

// if you want the binary data stream
alert(oXML.responseBody);