jQuery select CSS ( .bg-image:before )

Question

Sorry, I dont think it is duplicate of that question, since that post cannot solve my problem and they have different attribute

In my .html

<style>
    .bg-image:before {
        ...
        background: #333 url("1.jpg") no-repeat top center;
    }
</style>

and now I want to change the "1.jpg" to "2.jpg" using jQuery but I cannot select ".bg-image:before" to change it

I think I must use

style .bg-image:before { background... /style

to do an effect

Any suggestions? Thanks!