Fix SPA double-counted pageviews

Fix pageviews counted twice on single-page apps: duplicate router calls, the script included twice, tag manager history triggers, and checking with debug mode.

# Fix SPA double-counted pageviews

> Fix pageviews counted twice on single-page apps: duplicate router calls, the script included twice, tag manager history triggers, and checking with debug mode.

If pageviews are roughly double the visits you'd expect, or each page shows
up twice in the Live stream, two things are sending pageviews for each
navigation.

## Common causes

1. **Both automatic SPA tracking and a manual call.** You call
   `privatus.pageview()` in a router hook (`router.afterEach`,
   `useEffect` on the location, `onRouteChange`) while the tracker also
   follows `history.pushState`, `popstate` and hash changes. Remove your
   call, or switch the tracker to `data-spa="off"` and keep yours.
2. **The script is included twice**: in the layout and in a page, or by a
   plugin and by hand. Search the rendered HTML for `pa.js`. There should
   be exactly one. A framework integration plus a manual snippet is a
   common pair.
3. **A tag manager re-fires the tag** on "History change" triggers. Fire
   it only on page load: the tracker handles history changes itself.
4. **Zaraz SPA support** or similar tools re-injecting scripts on
   navigation.

## What the tracker already prevents

It won't send two automatic pageviews in a row for the same path, so a
router that pushes the same URL twice isn't double counted. The path is
the pathname, plus the fragment in hash mode (`data-spa="hash"`) and
route-like fragments (`#/about`, `#!/about`) in automatic mode.
`privatus.pageview()` always sends, by design.

## The `data-spa` modes

| Value | What the tracker follows |
|---|---|
| `auto` (default) | `history.pushState`, back and forward, and hash changes |
| `history` | `history.pushState` and back and forward only |
| `hash` | Hash changes only. Every `#fragment` counts as a page |
| `off` | Nothing. Only the first page load is sent, plus your own `privatus.pageview()` calls |

Check with `data-debug="true"`: each navigation should log exactly one
`[privatus] pageview`.

Näytä Markdown-muodossa

If pageviews are roughly double the visits you'd expect, or each page shows up twice in the Live stream, two things are sending pageviews for each navigation.

Common causes#

Both automatic SPA tracking and a manual call. You call privatus.pageview() in a router hook (router.afterEach, useEffect on the location, onRouteChange) while the tracker also follows history.pushState, popstate and hash changes. Remove your call, or switch the tracker to data-spa="off" and keep yours.
The script is included twice: in the layout and in a page, or by a plugin and by hand. Search the rendered HTML for pa.js. There should be exactly one. A framework integration plus a manual snippet is a common pair.
A tag manager re-fires the tag on "History change" triggers. Fire it only on page load: the tracker handles history changes itself.
Zaraz SPA support or similar tools re-injecting scripts on navigation.

What the tracker already prevents#

It won't send two automatic pageviews in a row for the same path, so a router that pushes the same URL twice isn't double counted. The path is the pathname, plus the fragment in hash mode (data-spa="hash") and route-like fragments (#/about, #!/about) in automatic mode. privatus.pageview() always sends, by design.

The `data-spa` modes#

Value	What the tracker follows
`auto` (default)	`history.pushState`, back and forward, and hash changes
`history`	`history.pushState` and back and forward only
`hash`	Hash changes only. Every `#fragment` counts as a page
`off`	Nothing. Only the first page load is sent, plus your own `privatus.pageview()` calls

Check with data-debug="true": each navigation should log exactly one [privatus] pageview.

Common causes#

What the tracker already prevents#

The data-spa modes#

The `data-spa` modes#