Escaping this javascript code in php

Question

I'm failing at escaping this code snippet that I only want to make visible on the page if a username is logged in. Then it just echoes that code, but as you can see, it's a large chunk that I need to escape. How do I go about that with this? Normally I don't have too much trouble with it myself but this code won't simply work otherwise.

//if user is logged in echo the code

if (isset($_SESSION['username'])){

echo '
    <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-PZWSZ2"
   height="0" width="0"   style="display:none;visibility:hidden"></iframe></noscript>
   <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
   new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
   j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
   '//www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
   })(window,document,'script','dataLayer','GTM-PZWSZ2');</script>
   ';
  }
?>

Google PHP nowdoc

bassxzero
– bassxzero

2016-10-13 19:10:31 +00:00
Commented Oct 13, 2016 at 19:10 — bassxzero
– bassxzero, Commented Oct 13, 2016 at 19:10
There's no PHP in the HTML part so just break out of PHP ?>

AbraCadaver
– AbraCadaver

2016-10-13 19:18:51 +00:00
Commented Oct 13, 2016 at 19:18 — AbraCadaver
– AbraCadaver, Commented Oct 13, 2016 at 19:18

AbraCadaver · Accepted Answer · 2016-10-13 19:21:58Z

The issue is that you have single quotes to encapsulate the HTML and more inside the HTML that haven't been escaped \'. See PHP Strings.

But to present an alternative since there is no PHP in the HTML, just break out of PHP:

<?php
if (isset($_SESSION['username'])){
?>
   <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-PZWSZ2"
   height="0" width="0"   style="display:none;visibility:hidden"></iframe></noscript>
   <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
   new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
   j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
   '//www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
   })(window,document,'script','dataLayer','GTM-PZWSZ2');</script>
<?php
  }
?>

Also see Alternative syntax for control structures that may be easier or more readable.

Mureinik · Accepted Answer · 2016-10-13 19:14:11Z

1

The simplest approach, IMHO would be to use a nowdoc:

$javascript = <<<'JAVASCRIPT'
<noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-PZWSZ2"
   height="0" width="0"   style="display:none;visibility:hidden"></iframe></noscript>
   <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
   new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
   j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
   '//www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
   })(window,document,'script','dataLayer','GTM-PZWSZ2');</script>
JAVASCRIPT

if (isset($_SESSION['username'])) {
    echo $javascript;
}

answered Oct 13, 2016 at 19:14

Mureinik

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2 Comments

AbraCadaver Over a year ago

Simplest would be not to use PHP ;-)

Mureinik Over a year ago

@AbraCadaver even better :-)

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