15

Amazon.com recently updated their javascript, and it's causing problems with some Opera browsers.

Their browser detection code looks like so, but it's faulty:

    function sitbReaderIsCompatibleBrowser() {
        if (typeof(jQuery) == 'undefined') {
            return false;
        } else {
            var version = jQuery.browser.version || "0";
            var splitVersion = version.split('.');
            return (
                   (jQuery.browser.msie && splitVersion[0] >= 6)  // IE 6 and higher
                || (jQuery.browser.mozilla && (
                       (splitVersion[0] == 1 && splitVersion[1] >= 8) // Firefox 2 and higher
                    || (splitVersion[0] >= 2)
                   ))
                || (jQuery.browser.safari && splitVersion[0] >= 500) // Safari 5 and higher
                || (jQuery.browser.opera && splitVersion[0] >= 9) // Opera 5 and higher
            );
        }
}

Nothing obviously wrong jumps out at me with this code, but I've never used jQuery before so I don't know.

Even though this code looks like it's attempting to let Opera users through, when I visit the page with Opera 9.64 I get an "unsupported browser" message. If I change Opera's settings to report itself as Firefox, the page works perfectly! With that in mind, I'm pretty sure it's a problem with the script and not the browser.

Any jQuery experts have a suggestion?

You can replicate the behavior by visiting any book on Amazon and clicking the "look inside this book" link.

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3
  • I'm using Opera 9.64 too but all that page is telling me is that Amazon Online Reader works best with IE > 6.0, Firefox > 1.5 or Safari > 2.0 Commented Mar 13, 2009 at 23:06
  • 3
    A good example of why browser detection and "unsupported browser" messages are almost always a lousy idea. Commented Mar 13, 2009 at 23:27
  • Well, this specific snippet of sniffing does indeed try to allow Opera, but as one of the answers below says Amazon has more browser sniffing elsewhere, including server-side sniffing, that isn't Opera-friendly. Commented Aug 6, 2012 at 3:13

9 Answers 9

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20

Prior to jQuery 1.3, you could use jQuery.browser:

if( $.browser.opera ){
  alert( "You're using Opera version "+$.browser.version+"!" );
}

From version 1.3, you should use jQuery.support instead.

Main reason for this is that should should avoid checking for browsers, as features may change from version to version, making your code obsolete in no time.

You should always try to use feature detection instead. This will allow you to see if current browser supports the feature you're trying to use, regardless the browser brand, version, etc.

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4 Comments

Spot-on. That's the code I'm looking for. Now hopefully Amazon will listen... :)
To be clear, jQuery 1.3+ doesn't actually remove jQuery.browser. "jQuery.browser will not be removed from future versions". But, you're right about feature detection.
+1. However: There are still legitimate use cases for using jQuery.browser. Example: Opera 11 happily supports the placeholder attribute on <input> elements, but does not allow styling of them. If we just used feature detection we'd end up with an un-stylable placeholder text. Instead, use jQuery.browser to check for Opera, then fall-back to a stylable alternative.
For future reference, it should be noted that jQuery 1.9 will remove jQuery.browser.
11

There is a special window.opera object which is present in all Opera 5+ browsers. So something as simple as:

if (window.opera && window.opera.buildNumber) { 
    // we are in Opera 
}

would be enough.

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4 Comments

No, it will not be enough. - Because, if somewhere in the page, you have element with id="opera", then if(window.opera) will be reporting true. In all browsers.
Then you could do this if (window.opera && window.opera.version) this will not be true in other browsers.
This might be useful for Opera mini: abeautifulsite.net/blog/2011/11/…
Doesn't work anymore. Use: isOpera() {return (navigator.userAgent.indexOf("OPR") !== -1)};
5

I check for Opera like this:

if (/Opera/.test (navigator.userAgent)) // do something

Why would you want jQuery?

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2 Comments

I don't--it's Amazon. I wrote their tech support, but as usual the folks at tech support had never heard of javascript. Aargh. I figure it's more productive to send them a fix than ask for help, since a fix might actually get forwarded to a programmer instead of a CSR.
Ahh, the best thing any web developer can do is to stop detecting browsers whatsoever :-)
5

It is much better to detect javascript capabilities rather than browser userAgent.

ie DOM, XmlHttpRequest, eventing model (event.target vs event.srcElement), ActiveX, Java etc

By focusing on the API functions that you will require, rather than a target browser you will create a more robust set of scripts, and inevitably less special casing.

This link here at opera will probably tell you more

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2

A very simple way from Opera themselves:

if (window.opera) {
    //this browser is Opera
}

Source: http://my.opera.com/community/openweb/idopera/

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1

The main reason why Amazon fails on Opera is because the send different code from the server side already... If you visit the same page with Firefox and then save that page and reopen it in Opera it works fine...

But they promised to fix that sometime in January...

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1

I think this way is the best
if ( window.opera.version() == 12) { }
This example check if opera version is 12. Very useful when I have problems with font-face in Opera.

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0

I don't know for sure ( i never really check for opera anyway) but if the built-in jQuery functionality doesn't detect opera, may be a bug with the jQuery which needs to be fixed. I would suspect if that's the case, it should get resolved fairly quickly.

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1 Comment

jQuery says it's Opera compatible, and the example page at docs.jquery.com/Utilities/jQuery.browser detects my browser perfectly. I don't think it's a jQuery bug. It has to be something about the way they are using it.
0

In current HTML5 times, you can also check for browser features instead often.

if (!window.FormData) { alert("xmlhttprequest L2 FormData interface not available"); }
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