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Using themes

Learn to share theme values across components with ThemeProvider.

Using a theme

A theme gathers colors and sizes into one object and offers it to the app. You wrap with ThemeProvider; children read values through props.theme.

Example: theme {primary: "blue"}; in the template color: ${props => props.theme.primary}. When the theme changes, everything updates.

Dark/light mode is easy with this structure.

ThemeProvider

You wrap ThemeProvider at the top of the app: <ThemeProvider theme={myTheme}><App /></ThemeProvider>. All styled components inside see the theme.

Keeping the theme object in its own file is clean; you change colors from one place.

This structure is the basis of consistent design systems.

Practice Themed button

Complete the skeleton. Create a styled component ThemedButton defined with styled.button\`color: ${props => props.theme.primary};\`. Export it.

Starter code

App.jsx
// Define ThemedButton here

Sample solution

App.jsx
const ThemedButton = styled.button`color: ${props => props.theme.primary};`;

export default ThemedButton;

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 How do you read a theme value in a template?

App.jsx
ThemeProvider provides props.theme.
  • props.theme.x Correct answer
  • this.theme
  • theme.x
  • window.theme

Explanation: Read it through props.theme.

2 Using themes: fill in the missing part

Question 
color: ${props => props.theme.____};
Answer 
color: ${props => props.theme.primary};

Explanation: You read the primary color via theme.primary.

3 Using themes: match the terms

Term Meaning
ThemeProvider Theme provider
props.theme Theme access
theme={x} Passing theme
{primary: "blue"} Theme object

All lessons in Beginner

1 React intro

  1. What is React?
  2. Setup and Vite
  3. Your first component
  4. Summary - React intro

2 JSX basics

  1. What is JSX?
  2. Expressions and curly braces
  3. Attributes and className
  4. Summary - JSX basics

3 Components

  1. Component logic
  2. Component tree
  3. Naming rules
  4. Summary - Components

4 Profile card

  1. Project: Profile card
  2. Avatar component
  3. Info list
  4. Assemble the card

5 Props

  1. What are props?
  2. Reading props
  3. Children prop
  4. Default props
  5. Summary - Props

6 Conditional rendering

  1. What is conditional rendering?
  2. Ternary operator
  3. Logical AND (&&)
  4. Early return
  5. Summary - Conditional rendering

7 List rendering

  1. What is list rendering?
  2. The key attribute
  3. Array to components
  4. Filtering and sorting
  5. Summary - List rendering

8 Shopping list

  1. Project: Shopping list
  2. Item component
  3. List body
  4. Empty state

9 Events

  1. Events
  2. The event object
  3. Form events
  4. Summary - Events

10 useState

  1. What is state?
  2. The useState call
  3. Updating state
  4. Multiple state values
  5. Summary - useState

11 Counter app

  1. Project: Counter app
  2. Number and buttons
  3. Decrement and reset
  4. Boundary control

12 Forms

  1. Controlled input
  2. Form submission
  3. Multiple fields
  4. Summary - Forms

13 Styling

  1. Styling with CSS
  2. CSS Modules
  3. Inline styles
  4. Summary - Styling

14 styled-components

  1. What is styled-components?
  2. Styling with props
  3. Using themes
  4. Summary - styled-components

15 useReducer

  1. What is useReducer?
  2. Action and state
  3. useState vs useReducer
  4. Summary - useReducer

16 useEffect

  1. What is useEffect?
  2. Dependency array
  3. Cleanup function
  4. Summary - useEffect

17 Context

  1. What is context?
  2. createContext
  3. Provider and useContext
  4. Summary - Context

18 useRef

  1. What is useRef?
  2. DOM access
  3. Timer example
  4. Summary - useRef

19 Todo app

  1. Project: Todo app
  2. Todo entry form
  3. Todo list
  4. Filter and summary

20 Beginner final

  1. Challenge: Weather card
  2. Challenge: Cart summary
  3. Challenge: Counter and reset
  4. Challenge: Dropdown menu