Detect Javascript capable browser with PHP?

rosscarlson

Sorry for the (maybe) dumb question, but I need to detect if the browser can do javascript using PHP? I need to get this into a PHP variable that I can read several times later in my app.

I've got a small JavaScript that sets the value in a form field that is hidden, and if the browser is capable it would set it to "yes" (it's default is now "no"). But how do I read this value without doing a submit? I know I can read it as $_POST'value'] after submitting, but I can't do a submit here (it would break other stuff).

So I guess my question is can you read the value of a form field WITHOUT it being submitted? Or is there another way to do this?

Thanks,

Ross

dagon

"phpSniff: HTTP_USER_AGENT Client Sniffer for PHP
Copyright (C) 2001 Roger Raymond ~ epsilon7@users.sourceforge.net"

can do that for you - of course it knows what browsers support what javascript versions -not if a user has disabled it or not.

drawmack

why don't you write an index.php that looks like this:

<?php
session_start();
$_SESSION['js_capable'] = 0;

if($_GET['Process'] == 'Yes') {
    $_SESSION['js_capable'] = 1;
    header('Location: main.php');
} //end if
?>
<html>
<head>
<title>My Site Title</title>
<body>
Look at my site's beautiful splash page. If you are not automatically redirected to the site then click <a href="main.php">here</a>.
<form action="<?=$PHP_SELF?>">
    <input type=hidden name="Process" value="No">
</form>

<script>
    document.forms[0].Process.value='Yes';
    document.forms[0].Process.submit();
</script>
</html>

js capable browsers won't even see this page.

rosscarlson

dagon,

Thanks for the tip on phpSniff. It works, but is VERY bloated for what I need. I've been chopping it up to get what I want but there is still just a ton there...

drawmack, thanks for the reply but you must not have read my original post very well, as I clearly said I can't do any kind of re-submit to the page (due to other functions/forms) Your code would do that (I actually already had that working).

Anyone else got a "light" way of doing this? There's got to be some little trick I can do...

Thanks,

Ross

mystrymaster

you can set it as a URL variable on all the possible links as well and read it from there

superwormy

You can detect if its a javascript CAPABLE with get_browser()
http://us4.php.net/get_browser

BUT you CANNOT detect if its ENABLED without a form submit. Period.

Drawmacks method is the best way.

rosscarlson

Yep, you're right, it is the best method, but I can't use it because of what my page does.

I'll try the other suggestion...

Thanks,

Ross

bobthedog

Unfortunately, I don't see any way you can do this without a page submit.

Detecting whether JS is available through the HTTP_USER_AGENT is all well and good, but this is easily modified and you can't guarantee any information is going to be there or be correct.

BUT - since JS requires not only JS to be available - but also enabled there is no way you can find this out without trying to run some JS in the first place and returning the result to your script.

The question is, why can't you do a page load??? If you wanted to be a bit more sly, you could create an invisible frame and do the detection in there, resubmitting to your server without the user knowing anything (unless of course they check out the source code etc)

rosscarlson

Thanks for the feedback everyone. Yep, you're right of course about the submit stuff. The reason I can't do a submit is that my app is really all just one page with a bunch of includes (maybe that's stupid but that's for another post...)

The issue is if I do an autosubmit everytime then when the user submits data to the page it would loose the other submit variables....

The idea I came up with is that my app has an installer. During the installer I could easily do the submit to check for it, then set the default variable to javascript being off. That's about the best thing I've got...

Thanks everyone for the input, it is appreciated...

Ross Carlson
http://jinzora.jasbone.com