I want to switch between this two functions every 5 seconds. The function changes the background image of a website in an :after element. 
I think I have to do it like this because there is no other way to access :after elements with jQuery. So it should work like a slideshow.

How can I achieve this?

```
function one(){  
var value = "url('/img/img1.png')"
$( "<style>#showcase:after { background-image: " + value + "; }</style>" ).appendTo( "head" )
}

function two(){  
var value = "url('/img/img2.jpg')"
$( "<style>#showcase:after { background-image: " + value + "; }</style>" ).appendTo( "head" )
}

```