Add condition to display back button

[prachigarg19]

Changes in this pull request:

• We need to implement a logic change on the mobile view such that if we do not pass a callback URL and reaches the page from an external then we will no longer provide the button as we cannot take the users back to the source they came from.
• If we are reaching the page from within the webapp, we will display the back button regardless of whether callback URL is provided or not.
• If callbackURL is provided we will display the back button regardless of whether the user came from external link or not.

=====================

• Show Cancel button instead of back button (in top panel)
• Show Cancel button only if there is a callback or if user visits from donate.plant-for-the-planet.org

@

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Name	Status	Preview	Comments	Updated (UTC)
donate-with-planet	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	May 16, 2023 1:32pm

[norbertschuler]

This implementation does not really work for me, as windows.origin is always the same value and when I hit the back button e.g. on the contact form page, I get redirected to the callback_url.

[norbertschuler]

Maybe use boolean state as for isMobile above?

[prachigarg19]

This is because I if the value if set to false at any point of time, it means that the user came from an external link and so I don't want to display the back button. Setting false initially would prevent me from updating the value and setting true would display the back button. Hence, I've set null as the initial value.

[norbertschuler]

Why not put the code of the function directly into the useEffect(() => {...}, [router]); instead of defining a new function storePathValues?

[norbertschuler]

This raises a warning about a type error for string | null.

[norbertschuler]

This could be just one line of code.

[sunilsabatp]

when I tried to visit from webapp to donation using donate button in the webapp , The back button was not visible for me
webapp-to-donation

need to review again

[mariahosfeld]

Checked this, when I have originally no callback_url and click on the back arrow from the contact details, then I also see the back button, that should be not visible in this case.