Re: Strange behavior on http://modpagespeed.com/defer_javascript.html

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Joshua Marantz

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Oct 15, 2012, 9:28:15 PM10/15/12

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defer_javascript is user-agent sensitive -- it won't work on all browsers. So if you are fetching from modpagespeed.com without one set, the filter will automatically turn itself off.

To test it from a script, set the UA to the same one used in Chrome, which you can find with something like http://whatsmyuseragent.com/.

-Josh

On Mon, Oct 15, 2012 at 8:45 PM, Jeff Winkler <wink...@gmail.com> wrote:

Hi-
I'm scripting some checks to verify page contents with and without MPS. Using the modpagespeed.com examples to learn and practice on. For some reason, defer_javascript is unchanged when fetched programatically -- despite having the X-Mod-Pagespeed header!

An simpler repro case in Groovy.. this fails:

String html= new URL('http://modpagespeed.com/defer_javascript.html?ModPagespeed=on&ModPagespeedFilters=defer_javascript').text

assert html.contains ('pagespeed.deferInit()')

Any ideas? This is really strange.
Thanks,
Jeff Winkler

----------

groovy> String html= new URL('http://modpagespeed.com/defer_javascript.html?ModPagespeed=on&ModPagespeedFilters=defer_javascript').text

groovy> assert html.contains ('pagespeed.deferInit()')

Exception thrown

Oct 15, 2012 8:44:07 PM org.codehaus.groovy.runtime.StackTraceUtils sanitize

WARNING: Sanitizing stacktrace:

Assertion failed:

assert html.contains ('pagespeed.deferInit()')

| |
| false
<html>
<head>

<title>defer_javascript example</title>
</head>
<body>


<p>
If defer_javascript is enabled, '*'s and images will appear before script
text. If not the script text will be interspersed with '*'s and images.

</p>
<script>
function sleep(ms) {

var sleep_now = Number(new Date());
while(sleep_now+ms>Number(new Date())) { var tmp = sleep_now; }

}
sleep(2000);
var state = 0;

</script>
<p>
<script src="rewrite_javascript.js" type="text/javascript" id="ext1">

</script>
</p>
<p>*</p>

<img src="images/Puzzle.jpg"><br/>
<p>*</p>
<script>

sleep(2000);
document.write('<p>Inline Script 1</p>');
</script>

<p>*</p>
<img src="images/BikeCrashIcn.png"><br/>
<p>*</p>

<script>
sleep(2000);
document.write('<p>Inline Script 2</p>');

</script>
<p>*</p>
<img src="images/Cuppa.png"><br/>

<p>*</p>
</body>
</html>

Kishore Simbili

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Oct 15, 2012, 9:29:03 PM10/15/12

to mod-pagesp...@googlegroups.com

Hi,

defer_javascript works only with certain user_agents. Are you using any userAgent for your requests?

It is supported only with modern browser userAgents like , chrome, firefox, safari and IE9 and above.

Try using any of those , and I think it should work.

Thanks,

Kishore

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