fix(gatsby-plugin-google-gtag): correct script to match google's current

[benomatis]

When taking the script from GA directly, it doesn't have this additional check for window.dataLayer, also the related documentation shows it without it.

gatsby/packages/gatsby-script/README.md

Line 40 in fc299ec

window.gtag = function gtag() { window.dataLayer.push(arguments); }

gatsby/docs/docs/reference/built-in-components/gatsby-script.md

Line 157 in fc299ec

window.gtag = function gtag() { window.dataLayer.push(arguments) }

[LekoArts]

https://developers.google.com/tag-platform/gtagjs/install shows a different snippet:

  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments)};
  gtag('js', new Date());

Can you also update all the docs that include this? Thanks!

[benomatis]

https://developers.google.com/tag-platform/gtagjs/install shows a different snippet:

  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments)};
  gtag('js', new Date());

Yes, indeed, I forgot to remove window from in front of dataLayer.push(arguments).

Can you also update all the docs that include this? Thanks!

Will do!

[benomatis]

@LekoArts should be done now.

[LekoArts]

Thanks 👍

[joaquingatica]

Came across this other older PR while troubleshooting an error in Safari and DuckDuckGo Browser: #11431, and appears to be the reason the window.dataLayer && window. check was introduced.

Not questioning the decision of removing it, just wanted to add context in case it was missing at the time of merging, or to anybody who comes across this issue again.

[benomatis]

@joaquingatica the changes in this PR are in line with GA's current manual install instructions of the GA4 tag, and in that snippet they only check window.dataLayer, not windows and then proceed to use dataLayer as a standalone function. It is further detailed in the description of the data layer.

I believe it must be happening for some other reason, most probably a browser plugin or privacy settings - this question on SO may provide some valid answers to such cases.