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1

This question already has an answer here:

I've run into an odd issue in a PHP script that I'm writing-- I'm sure there's an easy answer but I'm not seeing it.

I'm pulling some vars from a DB using PHP, then passing those values into a Javascript that is getting built dynamically in PHP. Something like this:

$myvar = (bool) $db_return->myvar;

$js = "<script type=text/javascript>
        var myvar = " . $myvar . ";
        var myurl = 'http://someserver.com/ajaxpage.php?urlvar=myvar';
       </script>";

The problem is that if the boolean value in the DB for "myvar" is false, then the instance of myvar in the $js is null, not false, and this is breaking the script.

Is there a way to properly pass the value false into the myvar variable?

Thanks!

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marked as duplicate by Benjamin Gruenbaum yesterday

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

3 Answers

up vote 17 down vote accepted

use json_encode(). It'll convert from native PHP types to native Javascript types:

var myvar = <?php echo json_encode($my_var); ?>;

and will also take care of any escaping necessary to turn that into valid javascript.

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1  
very clever solution Marc, and it works well! Thanks. I should also point out that the issue turns out to have been in casting it to a boolean-- if I cast to int instead, it brings back a 0/1 value and this can be passed to the JS as an int, and evaluated as true/false by JS normally. –  julio Apr 1 '11 at 19:20
    
awesome trick :D thanks –  Ashish Panwar Jan 22 '13 at 18:09
    
Works! Would be nice to know if this could be done without json trick. –  dev.e.loper Sep 20 '13 at 18:55
    
it could, but then you're responsible for producing valid javascript code. remember that json IS javascript... so build your own system when you can just use the perfectly good pre-built on? –  Marc B Sep 20 '13 at 18:59
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up vote 3 down vote

This is the simplest solution:

Just use var_export($myvar) instead of $myvar in $js;

$js = "<script type=text/javascript>
        var myvar = " . var_export($myvar) . ";
        var myurl = 'http://someserver.com/ajaxpage.php?urlvar=myvar';
       </script>";

Note: var_export() is compatible with PHP 4.2.0+

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up vote 2 down vote 
$js = "<script type=text/javascript>
    var myvar = " . ($myvar ? 'true' : 'false') . ";
    var myurl = 'http://someserver.com/ajaxpage.php?urlvar=myvar';
   </script>";
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var_export($myvar)? All you guys forgot var_export()... :) –  Wh1T3h4Ck5 Apr 1 '11 at 19:22
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