POC Monkey-patch history pushState and replaceState to listen to location changes

[zanderle]

Closes #157

[zanderle]

@humitos this just does the monkey-patching for now (haven't added any listeners yet). Do we want to do a test-build with this, to see if it correctly picks up the "page changes", before we move on to the next step?

[humitos]

I did a small review and left a few questions.

[humitos]

Suggested change

	* Setup events firing on history pushState and replaceState
	*
	* This is needed when addons are used in SPA. A lot of addons rely
	* on the current URL. However in the SPA, the pages are not reloaded, so
	* the addons never get notified of the changes in the URL.
	*
	* While History API does have `popstate` event, the only way to listen to
	* changes via pushState and replaceState is using monkey-patching, which is
	* what this function does. (See https://stackoverflow.com/a/4585031)
	* It will fire a "pushState" or "replaceState" event, depending on which method was called.
	* Setup events firing on history `pushState` and `replaceState`
	*
	* This is needed when addons are used in SPA. A lot of addons rely
	* on the current URL. However in the SPA, the pages are not reloaded, so
	* the addons never get notified of the changes in the URL.
	*
	* While History API does have `popstate` event, the only way to listen to
	* changes via `pushState` and `replaceState` is using monkey-patching, which is
	* what this function does. (See https://stackoverflow.com/a/4585031)
	* It will fire a `READTHEDOCS_URL_CHANGED` event, on `pushState` and `replaceState`.

[humitos]

Do we need to make the distinction between these two events for our purpose? I think it will be better to expose just READTHEDOCS_URL_CHANGED and always trigger this event either if it's pushState or replaceState. What do you think?

[zanderle]

Yeah, we can do it like that 👍

[humitos]

Here is where I think we should create new Event(READTHEDOCS_URL_CHANGED) or similar.

[humitos]

Do we want to do a test-build with this, to see if it correctly picks up the "page changes", before we move on to the next step?

How hard would it be to create a simple example for this using the index.html page from this repository?

I tested using test-builds locally and I can confirm the custom method is called when changing pages on Docusaurus and Material for MkDocs (I added some small console.log) --but I don't want you to deal with my current setup since it's a complex.

[zanderle]

Do we want to do a test-build with this, to see if it correctly picks up the "page changes", before we move on to the next step?

How hard would it be to create a simple example for this using the index.html page from this repository?

I tested using test-builds locally and I can confirm the custom method is called when changing pages on Docusaurus and Material for MkDocs (I added some small console.log) --but I don't want you to deal with my current setup since it's a complex.

I think I can make it work locally, to develop, and then I'll ask you to do a proper test on your setup

[agjohnson]

Changes here seem fine, no additions to the notes here 👍