fix(v2): GTM, send page_view events on navigate

[govardhan-srinivas]

Closes #3047

Motivation

Was following Facebook open-source immersion program, recently did my PR to the Material UI repo, So thought to give a try.

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

Followed the Google Analytics document while implementing pageviews.

Demo site with this change: https://govardhan-srinivas.github.io/docusaurus-blog-mode/
Screenshot of pageviews in google analytics

Related PRs

(If this PR adds or changes functionality, please take some time to update the docs at https://github.com/facebook/docusaurus, and link to your PR here.)

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[slorber]

Thanks

LGTM, but prettier failure

[govardhan-srinivas]

While I was debugging few minutes back I found out that adding the parameter 'send_page_view' to existing config would also send page views to Google analytics.
Here I have created a gist for it.

@slorber @yangshun Please let me know how we should proceed?

[slorber]

@govardhan-srinivas I don't know gtag unfortunately and don't even have an account.

What do you feel is the right solution, and have you actually tested it live on a real Docusaurus site and GTM account to ensure it works?

Also if you hesitate between solutions, please help me help you by linking to the relevant parts of the docs

[govardhan-srinivas]

@slorber I was refering this link, I find 2 ways of capturing pageviews:

1. Automatically captured with this snippet
2. Manually capture it when there is a location change[Existing implementation in the pull request].

Both does the same functionality but I feel second one has more advantage over the first, As we can set manual break points when to trigger the page view event.
Eg: when we have SPA and infinite scrolling content[like facebook posts], then we can add manual trigger event considering each section as a virtual page within.

If we agree on above thing, we can merge this PR.

[slorber]

Thanks, this solution looks fine