Javascript – Detect 64-bit or 32-bit Windows from User Agent or Javascript

64-bitjavascriptoperating systemuser-agent

I want to offer the right version of a download. The versions I have are:

32-bit Windows
64-bit Windows
Linux

Detecting Linux using the User Agent field is easy; but is it possible to reliably figure out if Windows is 32-bit or 64-bit?

Users might be using weird browsers – IE and Firefox are common, and we probably have an Opera user somewhere; maybe a Chrome user too. I know that 64-bit Windows 7 ships with 32-bit and 64-bit versions of IE, and I'd like to send them both the 64-bit version of my download.

(Edited to add: I know that I should provide all the options, and I will. But people don't read the options. So I wanted to provide the right download by default, to improve usability. Of course, while this is helpful if I get it right, it's extremely unhelpful if I get it wrong. And from the answers so far, it doesn't look like there's a reliable way of doing this).

Best Answer

Try this, looks for WOW64 (32-bit on 64-bit) or Win64 (native 64-bit) in the user-agent string.

    if (navigator.userAgent.indexOf("WOW64") != -1 || 
        navigator.userAgent.indexOf("Win64") != -1 ){
       alert("This is a 64 bit OS");
    } else {
       alert("Not a 64 bit OS");
    }

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Javascript – How to detect if JavaScript is disabled

I'd like to add my .02 here. It's not 100% bulletproof, but I think it's good enough.

The problem, for me, with the preferred example of putting up some sort of "this site doesn't work so well without Javascript" message is that you then need to make sure that your site works okay without Javascript. And once you've started down that road, then you start realizing that the site should be bulletproof with JS turned off, and that's a whole big chunk of additional work.

So, what you really want is a "redirection" to a page that says "turn on JS, silly". But, of course, you can't reliably do meta redirections. So, here's the suggestion:

<noscript>
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    </style>
    <div class="noscriptmsg">
    You don't have javascript enabled.  Good luck with that.
    </div>
</noscript>

...where all of the content in your site is wrapped with a div of class "pagecontainer". The CSS inside the noscript tag will then hide all of your page content, and instead display whatever "no JS" message you want to show. This is actually what Gmail appears to do...and if it's good enough for Google, it's good enough for my little site.

Javascript – the best way to add options to a select from a JavaScript object with jQuery

The same as other answers, in a jQuery fashion:

$.each(selectValues, function(key, value) {   
     $('#mySelect')
         .append($("<option></option>")
                    .attr("value", key)
                    .text(value)); 
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Best Answer

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