The approach you mentioned sort of works but a) it does require refactoring backend code (which by itself may already be a non-starter depending on whether you're dealing w/ a "old guard" backend tech lead, for example) b) it opens up potential security holes if implemented as you describe, c) you might lose SEO visibility and/or fail more catastrophically (i.e. a js exception might blank out the page entirely, vs merely breaking toggling), etc.
A more nitpicky code reviewer might also question the usage of babel off of a CDN if you went with a no-build JSX approach, the usage of window, etc.
By comparison, the vue snippet would be trivial, "production worthy" and it handles all the things above correctly.
I don't have a lot of experience with Vue, but I don't follow. You include Vue.js from CDN in a `script` tag, and then just add the `v-for` and `v-if` annotations to your HTML? How does Vue get the data, to properly iterate over it in `v-for` or check in `v-if`?
I'm really curious because I feel I'm missing some piece of puzzle here.
EDIT:
Previous HTML outputted by for loop in backend template:
<ul>
<li>
<h2>Question 1</h2>
<p>Answer 1</p>
</li>
<li>
<h2>Question 2</h2>
<p>Answer 2</p>
</li>
</ul>
<ul>
<li>
<h2>
<button v-on:click="expanded = 1">
Question 1
</button>
</h2>
<p v-if="expanded === 1">Answer 1</p>
</li>
<li>
<h2>
<button v-on:click="expanded = 2">
Question 2
</button>
</h2>
<p v-if="expanded === 2">Answer 2</p>
</li>
</ul>
You don't have to refactor much I think. You can inject the data into global scope in your PHP template, before you include React script. I'd do something like `window.__PAGE_DATA__ = "<?php echo json_encode($data) ?>";`.
Then, in your React code you'll be able to access it in a pretty idiomatic way for React. Instead of calling `fetch` or something similar, you'll have to call `JSON.parse(window.__PAGE_DATA__)`. You have to use `try`/`catch` block around it as well to handle errors from JSON parsing - just like you have to have the same block around `await` calls. You can treat the data as immutable to a degree as well - accidental local property updates will not get to the global scope, you'll have to set the property in `window` object.
I've used React in a few projects, embedding it into a Wordpress website using this approach. Seems to work well for me, but YMMV.