array.push() but no results in array?

Question

Link here.

<script>
  dataLayer = [];
</script>

<!-- Google Tag Manager -->
<noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-XXXX" // disguised GTM snippet
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-PB4S9P');</script>
<!-- End Google Tag Manager -->

<script>
  dataLayer.push({
    'event':'nevent',
    'eventCategory': 'form submissions',
    'eventAction': 'saw form',
    'eventLabel': '[GPI - Donation Request Form]'  // e.g. Newsletter signup form - NEW SITE
  });  
</script>

When I visit the link and open the console and type dataLayer I expected to see the object. But I cannot.

When I am on the page if I cut n paste the dataLayer.push({}); it works - I see it added to the dataLayer.

So how could it be that the dataLayer array is not populated with the contents of the push below it?

It works for me. When I visit the page and type dataLayer into the console. I get the object. — Pointy
– Pointy, Commented Aug 6, 2015 at 17:59
The GTM script probably loads after your push method and overwrites your dataLayer variable. Try putting it inside some variant of document.ready — Jan
– Jan, Commented Aug 6, 2015 at 17:59
@Jan yes I think that's probably the issue. OP that Google thing is simply overwriting the value of your variable. — Pointy
– Pointy, Commented Aug 6, 2015 at 18:01

Siguza · Accepted Answer · 2015-08-06 18:05:30Z

4

The provided code doesn't match the one on your page.
Your page is (somewhat) minified, i.e. it has no line breaks.
This conflicts with your end-of-line-style comment (//):

<script>  dataLayer.push({    'event':'nevent',    'eventCategory': 'form submissions',    'eventAction': 'saw form',    'eventLabel': '[GPI - Donation Request Form]'  // e.g. Newsletter signup form - NEW SITE  });  </script>

It cuts of the });, resulting in a syntax error.
Nevertheless though, I do get a result for typing dataLayer in the console:

[
    {
        "gtm.start": 1438884079089,
        "event": "gtm.js"
    },
    {
        "event": "gtm.dom"
    },
    {
        "event": "gtm.load"
    }
]

edited Aug 6, 2015 at 18:05

answered Aug 6, 2015 at 18:02

Siguza

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5 Comments

Jan Over a year ago

That's one poor minifier that doesn't remove comments

Siguza Over a year ago

@Jan It also doesn't even collapse multiple spaces into one... doesn't break functionality, but makes all other minification basically pointless.

Doug Fir Over a year ago

Thank you so much. Accepting when the time limit comes off. So, how did you spot/realise that? Just so I know how to tell in future?

Jan Over a year ago

Well, visiting the link you posted gives a console error, so I'm guessing that was clue #1 ;) stackoverflow.com/tags/javascript/info <- Check the "debugging" section

Siguza Over a year ago

@DougFirr The Chrome console told me that there's a syntax error, and I saw that your code was minified, so I dropped it into an HTML beautifier (just my favourite, not mine or anything), and then I was basically just saw that there's no bracket or anything after an indented block.

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