fix(donation-form): Don't clear form fields via JS if no Give form is present on the page

[mathetos]

User Story

As a Give user, I want to be able to navigate through my site without any JS errors.

Current Behavior

As reported here:
https://wordpress.org/support/topic/js-errors-when-you-hit-the-back-button/#post-10211556

The Give plugin includes some JavaScript that is meant to clear a donation form if you fill out a form and then use the “Back” button in your browser to go back to a page with the form. That’s great, but the problem is that it tries to clear the data on every page, not just on pages with a donation form, so if you go back to a page without a form, you get an error: TypeError: e(...).find(...)[0] is undefined
The problem is in assets/js/frontend/give.js, line 108.

Expected Behavior

I expect to be able to navigate back on pages that do NOT have a Give form and not encounter a JS error on them.

Possible Solution

Detect if the page has a Give form and only target the Give form pages if they are present. Optionally, only enqueue our Give JS on pages where a Give form exists.

Steps to Reproduce

1. Go to a page on your site that does NOT have a Give form.
2. Navigate to another page on your site that also does not have A Give form.
3. Hit your browsers back button.
4. Confirm the JS error described above.

Related

• Plugin loads resources in non-performant ways. #1211

[ravinderk]

@mathetos This issue already has been resolved. Please confirm: #3019

[mathetos]

Thanks @ravinderk apologies I didn't search existing issues beforehand. Great work!