React

by Arthur Lutkevichus

HTML

<div id="app"></div>

CSS

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}

li {
  margin: 8px 0;
}

h2 {
  font-weight: bold;
  margin-bottom: 15px;
}

.done {
  color: rgba(0, 0, 0, 0.3);
  text-decoration: line-through;
}

input {
  margin-right: 5px;
}

React

const TodoApp = () => {
	const [state, setState] = React.useState({});
  
  React.useEffect(() => {
  	console.log("parent");
  });
    return (
      <div>
        <Child setter={(data) => setState({data})} state={state} />
      </div>
    );
}

const Child = ({setter, state}) => {

	React.useEffect(() => {
  	console.log("Child rerender");
  });
  
  console.log(state)
  
	return (
  	<div onClick={() => setter({d: Date.now()})}>
    Click me <code>{JSON.stringify(state)}</code>
    </div>
  );
};

ReactDOM.render(<TodoApp />, document.querySelector("#app"))