Before and After pseudo classes used with styled-components - reactjs

Question

What is the proper way to apply :before and :after pseudo classes to styled components?
I know that you can use
&:hover {}
to apply the :hover pseudo class to a styled-component.
Does this work for All pseudo elements like before and after?
I have tried using the &:before and &:after strategy with some rather complex examples and i'm not sure if my attempts are not working because i've got something wrong with my example or it just doesn't work like that.
Does someone have some insight on this? Thank you.

Answer 1

Pseudo-selectors in styled-components work just like they do in CSS. (or rather, Sass) Whatever isn't working is likely a problem in your specific code, but that's hard to debug without seeing the actual code!
Here is an example of how to use a simple :after:
const UnicornAfter = styled.div`
&:after {
content: " 🦄";
}
`;
<UnicornAfter>I am a</UnicornAfter> // renders: "I am a 🦄"
If you post your code I'll likely be able to help debug your specific issue!

Answer 2

This will print the triangle at middle of the div.
const LoginBackground = styled.div`
& {
width: 30%;
height: 75%;
padding: 0.5em;
background-color: #f8d05d;
margin: 0 auto;
position: relative;
}
&:after {
border-right: solid 20px transparent;
border-left: solid 20px transparent;
border-top: solid 20px #f8d05d;
transform: translateX(-50%);
position: absolute;
z-index: -1;
content: "";
top: 100%;
left: 50%;
height: 0;
width: 0;
}
`;

Answer 3

This is good and simple answer:
https://stackoverflow.com/a/45871869/4499788 by mxstbr
but for elements requiring more complex logic I prefer this approach:
const Figure = styled.div`
${Square}:before,
${Square}:after,
${Square} div:before,
${Square} div:after {
background-color: white;
position: absolute;
content: "";
display: block;
-webkit-transition: all 0.4s ease-in-out;
transition: all 0.4s ease-in-out;
}
`;

Answer 4

As an object (note the double quotes):
const Div = styled.div({
'&:before': {
content: '"a string"',
},
})

Answer 5

Adding to #mxstbr answer
Note that when you want to render before based on props, don't forget to wrap it with double quotes (or single quotes) , example:
const Button = styled.button`
&:before {
content:"${(props)=>props.theme==='dark'?'dark theme':'white theme'}";
}
because
content:${(props)=>props.theme==='dark'?'dark theme':'white theme'};
will not work

Answer 6

Can try like this.
It works perfectly fine
var setValue="abc";
var elementstyle = '<style>YourClass:before { right:' + abc + 'px;}</style>'
$(".YourClass").append(setValue);
var rightMarginForNotificationPanelConnectorStyle = '<style>.authenticated-page.dx-authenticated .dx-notification .dx-notification-dialog.dx-content-frame:before { right:' + rightMarginForNotificationPanelConnectorWithBadge + 'px;}</style>'
$(".authenticated-page.dx-authenticated .dx-notification .dx-notification-dialog.dx-content-frame").append(rightMarginForNotificationPanelConnectorStyle);