Creating a theme just to deploy a single page

Question

I'm working on creating a simple single-page web app for an art project. This is mostly a lot of JavaScript, and a custom UI. I was told early on that the organisation commissioning the piece will provide web hosting on their site. Now I've found out that their site uses Wordpress, and it looks like I'll have to kind of hack the framework to deploy a single HTML file and associated resources.

From reading around it seems the simplest solution would be to create a new theme, a new page, and apply that theme to that one page. My question is - if that is the best route - what is the minimum I would need to do to get that working?

I've read that the minimum requirements for a Wordpress theme are a style.css with a header comment, and an index.php. I'm wondering, could I simply save my HTML file as index.php, without it containing any actual PHP code, and deploy it that way? Or perhaps I need to save it as page.php and leave the index.php as the default minimal code? Are there any requirements beyond having those two files?

Also, since I have been given full admin access to their site, and my first priority is not to mess with it in any way, is there anything I should bear in mind to ensure my theme doesn't interfere with the rest of the site?

Answer 1

Developing a theme is pretty safe. You won't wreck anything. The minimum you need is style.css with the following header:

/*
Theme Name: example
*/

Then save your html file as index.php and add that too. If you have an html file and save it as a php file, it'll be fine. If it contains no actual php code, it'll just come out exactly the same. Then activate the theme, and the website will simply serve your index.php page every time. Not exactly what wordpress was designed to do, but no reason why that wouldn't work.

That said, my recommendation would be to invest a little time learning some of the working parts with WordPress and, even perhaps in time, leveraging some of its actual potential. It's a really, really great platform for a web developer to work from.

Edit:

Based on discussion in the comments, I think the actual solution to this will be to use a child theme along with one of two options for creating a template for a specific page.

First, a comment on child themes: The reason for this is so that you don't have to make edits to the theme currently running. This will allow it to receive updates without deleting the changes you make. More on child themes here and here. Then, you can use either a globally accessible page template, discussed here, or (and this is the one I would recommend) a page template applied to just one page, as discussed here.

Make your child theme by making a new theme directory called whatever you want, containing an empty file called functions.php (You don't have to use it, just have it here) and style.css with a header like this one:

/*
Theme Name: Example Child Theme
Template: existing-theme-directory-name
*/

Activate your child theme, and at this point nothing should change.

Then make a page in Wordpress which you can leave blank, just publish it to get your URL. (take note of the page's slug. If you miss it, an easy way to find it is click "quick edit" from the screen that shows all the pages) Then rename your HTML file page-my-page-slug.php (obviously using the page slug you collected earlier) and add it to your child theme directory. That file will now be served every time your page's URL is requested.