How to make buttons appear randomly?

If anyone can help,
I’d like to add an effect to buttons on my home page. When the page loads, I’d like the buttons to be invisible, then the alpha would be raised randomly on each button until they are all fully visible. Kind of an off/on kind of thing.
Anyone know what I mean? I cant find an example anywhere,I’ll keep looking.
But if someone can help, I’d greatly appreciate.