A way to wiev the wallpost before its posted?

I know it's probably not something that can be done, but the thought of being able to see how the wall post will look with the codes applied before posting it is really appealing. Right now, I have to delete and repost every time I notice the spacing is off, and I keep doing it repeatedly. CodePen and similar tools don’t help much, since they don’t quite match how it actually looks on the page.