react-native-theme-style

The problem

You want to:

• Apply styles to your react-native component according to a theme
• not use styled-components because of various reasons (Jest/Flow/etc issues)
• have a fully typed theme (Flow and Typescript support)
• A lightweight solution which is plain React and use the power of Hooks and context

Welcome to react-native-theme-style.

Usage

You must have React-Native 0.59+ installed

1. Install

yarn add react-native-theme-style

1. Create your theme context

// ./src/theme.jsx
 
import * as React from "react";
import { configureTheme } from "react-native-theme-style";
 
const defaultTheme = { color: "red" };
export const ThemeContext = React.createContext(defaultTheme);
 
export const useTheme = configureTheme(ThemeContext);

1. Wrap your app within the theme context

//./App.jsx
// ... imports going here
import {ThemeContext} from "./src/theme";
 
//... App class going here
render() {
    return (
    <ThemeContext.Provider>
      <App />
    </ThemeContext.Provider>
    );
}

And then in your functional components (on class components it won't work because of hooks running behind the hood) you can do:

// ./src/Foo.component.jsx
import { Text, View } from "react-native";
import { useTheme } from "./theme";
 
export const Foo = () => {
  const stylings = useTheme(styles);
  return (
    <View>
      <Text style={stylings.bar}>Hello React native</Text>
      <Text style={stylings.foo}>Hello Theme</Text>
    </View>
  );
};
 
const styles = {
  bar: {
    color: "yellow"
  },
  foo: theme => ({
    color: theme.color
  })
};

Optionally, if you want to evaluate the styles according to some value, you can pass a second parameter to useTheme:

// ./src/Foo.component.jsx
import { Text, View } from "react-native";
import { useTheme } from "./theme";
 
export const Foo = () => {
  const stylings = useTheme(styles, { isActive: true });
  return (
    <View>
      <Text style={stylings.bar}>Hello React native</Text>
      <Text style={stylings.foo}>Hello Theme</Text>
    </View>
  );
};
 
const styles = {
  bar: {
    color: "yellow"
  },
  foo: (theme, params) => ({
    color: params.isActive ? theme.color : "brown"
  })
};

Typescript/flow

// ./src/theme.tsx
 
import * as React from "react";
import { configureTheme, ThemeStyle } from "react-native-theme-style";
 
const defaultTheme = { color: "red" };
const ThemeContext = React.useContext(defaultTheme);
 
export const useTheme = configureTheme(ThemeContext);
 
// Typings support
export type ThemeType<T> = ThemeStyle<{ color: string }, T>;

and then:

// ./src/Foo.component.jsx
import { Text, View } from "react-native";
import { useTheme, ThemeType } from "./theme";
 
export const Foo = () => {
  const stylings = useTheme(styles, { isActive: true });
  return (
    <View>
      <Text style={stylings.bar}>Hello React native</Text>
      <Text style={stylings.foo}>Hello Theme</Text>
    </View>
  );
};
 
const styles: ThemeType<{ isActive: boolean }> = {
  bar: {
    color: "yellow"
  },
  foo: (theme, params) => ({
    color: params.isActive ? theme.color : "brown"
  })
};