fix(vue): incorrect view rendered when using router.go(-n)

[bentleyo]

resolves #28201

This PR fixes the navigation issue related to router.go that was identified in issue #28201. After working on this issue I realised that @xxllxhdj has already created a PR for this in #29847. While their fix is great, I have added tests to replicate the issue, reused existing code and undefined will be returned in unexpected situations - which matches the existing functionality.

What is the current behavior?

If a user navigates from /home -> /pageA -> /pageB -> /pageC -> back to /pageB -> then router.go(-2) is called the URL will be updated to /home correctly, but the app will try to render /pageA.

This happens for any delta < -1.

What is the new behavior?

The app will correctly render /pageA, which matches the URL.

Does this introduce a breaking change?

• Yes
• No

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Name	Status	Preview	Comments	Updated (UTC)
ionic-framework	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Oct 22, 2024 8:18pm

[bentleyo]

The main problem was that when using findLastLocation with deltas less than -1, the code no longer checked relative to the specified route. My code change fixes this 😄

[bentleyo]

@brandyscarney just a heads up, this PR relates to one assigned to you here: #29877

[bentleyo]

@thetaPC are you able to check this one for me and let me know if any changes required on my end to get this one through? 🙏

[thetaPC]

Thank you for submitting a PR!

I noticed you removed the if statement from the code. I'd love to understand your reasoning behind that change.

[bentleyo]

Hi @thetaPC thanks for the review!

The if statement I've removed was originally added to handle the situation where delta is less than -1. In that situation what it does is return the location delta many steps back from the end of the history stack.

if (delta < -1) {
  return locationHistory[locationHistory.length - 1 + delta];
}

However, this wasn't correct behaviour. There is a routeInfo passed into the function and the returned location should be delta steps back from that. Not back from the end of locationHistory.

This is why the bug reported in the issue was happening.

I've made it so it handles both situations using that same code. This is mostly reusing the code that was in the else statement.

That code essentially searches backwards through the history stack until it finds routeInfo and returns its parent (handling the delta -1 situation). I realised I could use index of that location in the array + delta to return the correct location.

I've added tests to handle the situations and ensure the behaviour works as expected. Let me know if you need any more details :)

[thetaPC]

LGTM, thank you!

[thetaPC]

Gave @xxllxhdj co author credit as the team decided to go with this approach. Thank you everyone!