> Anything that happens before your content gets to the browser is back-end by definition.
Huh? I didn't think that was in question.
> If you control the blogging software and/or the template, it would be trivial to replace the last space with when rendering the page.
No disagreements here.
> I wouldn't be surprised if somebody already wrote a WordPress plugin to do this
I'm sure there is too[1].
Sure. But if you want to do this before "they even get to the browser", it's not going to be a "non-back-end solution". Anything that happens before your content gets to the browser is back-end by definition.
If you control the blogging software and/or the template, it would be trivial to replace the last space with when rendering the page. Good ol' string manipulation, maybe a regexp or two. No need for JavaScript. I wouldn't be surprised if somebody already wrote a WordPress plugin to do this.