Using styled components with Typescript, prop does not exist?

Question

Here is my styled component.

import * as React from 'react';
import styled from 'styled-components';
import { ComponentChildren } from 'app-types';

interface Props {
    children: ComponentChildren;
    emphasized: boolean;
}

const HeadingStyled = styled.h2`
    ${props => props.emphasized && css`
        display: inline;
        padding-top: 10px;
        padding-right: 30px;
  `}
`;

const Heading = (props: Props) => (
    <HeadingStyled>
        {props.children}
    </HeadingStyled>
);

export default Heading;

I get warnings that:

• Property 'emphasized' does not exist on type 'ThemedStyledProps<DetailedHTMLProps<HTMLAttributes<HTMLHeadingElement>, HTMLHeadingElement>, any>'.
• Cannot find name 'css'. Did you mean 'CSS'?

How can I get this to work?

Answer 1

• The styled component will have to specify the prop to pass to the component like styled("h2")<IProps>. You can read more about the pattern from documentation
• css is not required here, it is added as a helper when you need to actually return CSS from a function. Check out conditional rendering.

Taking these into account, the component becomes:

const HeadingStyled = styled("h2")<{emphasized: boolean}>`
  ${props => props.emphasized && `
    display: inline;
    padding-top: 10px;
    padding-right: 30px;
  `}
`;

A use-case for css