Clone Coding Repository for “React WebGame” Course of ZeroCho

Lecture Link:

  • Lecture Language: Korean

Purpose / Goal

  • To familiarize the concept of React
  • Have the first experience in making web applications using React framework
    • Build some simple games using React

What I Learn

  • node packages for React Dev Environment
    • React
      • react: React Core
      • react-dom: Connect React and DOM
    • Babel
      • @babel/core: Babel Core
      • @babel/preset-react: Transfiling React JSX
      • @babel/preset-env: Transfiling ES6+ Codes
    • Webpack
      • webpack: Webpack Core
      • webpack-cli: Use Webpack on command line interface
      • webpack-dev-server: Build webpack in-memory and run development server
      • babel-loader: Transfiling JSX and ES6+ syntax
      • style-loader: Wrap and inject compiled CSS file
      • css-loader: Interpret CSS file so that JavaScript can understand
      • html-webpack-plugin: Inject bundled JavaScript files to HTML file
      • mini-css-extract-plugin: Separate CSS files
  • React.Component is building structure of React elements that will be appear on the screen.
    • All components should extends React.Component.
    • All components should override render() function.
    • Components may have state.
      • state is something that is modifiable inside the component.
      • use setState() to change state of the component.
        • Only used for something that needs to be changed manually
  • React.createElement(type, [props], [… children]) generates new React Elements of given type.
    • type can be tag name of HTML elements or React Component type (class or function) name.
    • prop contains HTML properties of the element.
      • Should be expressed in object format.
    • Can use JSX (JavaScript + XML) format (using HTML-shaped Tags) instead of React.createElement().
      • HTML expression inside JavaScript causes error;
        therefore, we need Babel to support JSX syntax.

        • To use Babel, type of script should be text/babel.
      • JavaScript code should be placed in curly bracket (e.g.: <div>{... some js code ...}</div>).
    • React.Fragment is used to group a list of chlidren without adding extra nodes to the DOM.
      • Help removing meaningless <div>.
      • Notation: <React.Fragment> ... </React.Fragment> or <> ... </>
  • Recommend NOT to mix JSX and JS Codes.
    • JavaScript logics can be implemented as Class Methods.
  • ReactDOM.render() renders a React element into the existing DOM.
    • This function actually draws the React Components to the web browsers.
    • React need at least one element (the root div<div id='root>) to render the React components inside.


Times Table Game

Followed lecture contents to build simple Times Table game.
Used React Class to build application.

Feature List (From Lecture)

  • Randomly select two number and ask user for the answer of multiplication.
  • Display the result of quiz.
  • Wrote codes in the browser (Importing JavaScript from CDN)

What I added/modified

  • Setup React Development Environment (Use Babel and Webpack)
    • Use ESLint and Prettier for code styling
  • Display correct answers if wrong
  • Design for both mobile and desktop site
Demo Image of

Code Link:
Demo Link:


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