React

by Humphry Huang

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 obj =  { a : 1 }
let i = 0

function TodoApp() {
	const [s, setS] = React.useState(obj)
  console.log(`render #${++i}`)
  return (
  	<React.Fragment>
    	<div>{JSON.stringify(s)}</div>
      <button
        onClick={() => setS(obj)}
      >
        update
       </button>
    </React.Fragment>
  )
}

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