One of the most useful tricks I learned when I started styling screens in React Native was how to conditionally apply CSS to a container.

Some of the most common use cases were reusing a component in a context where it has a slightly different style, display bottom border to all elements in a list except the last element, change input style on focus etc.

Now, let’s look at an example together.

Photo source: freepik.com

Firstly, run npx create-expo-app styling-app to create a new Expo project. Next, let’s cd into styling-app and install styled components:

npm install --save styled-components

#or

yarn add styled-components

Finally, open the app in your favorite code editor and run it. If you want to change a single style property you can pass a prop to a container and conditionally apply a style, depending on that prop.

import { Text } from 'react-native';
import styled from "styled-components/native";

export default function App() {
    return (
        <DashboardContainer>
            <Text>Register to your recycling account today!</Text>
            <ButtonContainer isMain={true}><Text>Continue</Text></ButtonContainer>
            <ButtonContainer><Text>Go back</Text></ButtonContainer>
        </DashboardContainer>
    );
}

const DashboardContainer = styled.View`
  flex: 1;
  alignItems: center;
  justifyContent: center;
`

const ButtonContainer = styled.TouchableOpacity`
  padding: 8px;
  margin-vertical: 6px;
  border-radius: 4px;
  background-color: ${({isMain}) => isMain? '#93D976': '#F2F2F2' }
`

As you can see in the example above, I pass isMain prop to the ButtonContainer and if isMain is a truthy value the background color is green, otherwise it changes to gray. Here's how our buttons should look:

In case you need to render multiple stylings you can use template literals:

const ButtonContainer = styled.TouchableOpacity`
  padding: 8px;
  margin-vertical: 6px;
  border-radius: 4px;
  ${({ isMain }) =>
    isMain && `
            background-color: #93D976;
            border-color: #013220;
            border-width: 1px;
          `}
`

Or if you use TypeScript, you can type check the prop:

const ButtonContainer = styled.TouchableOpacity<{isMain: boolean}>`
  padding: 8px;
  margin-vertical: 6px;
  border-radius: 4px;
  ${({ isMain }) =>
          isMain && `
            background-color: #93D976;
            border-color: #013220;
            border-width: 1px;
          `}
`

Still curious to learn more about how styled components work? Check styled components documentation. Good luck! 🚀

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