Controlled Input Example

For the lesson about controlled inputs

by Breathe Code

HTML

<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
<div id="container">
    <!-- This element's contents will be replaced with your component. -->
</div>

Babel + JSX

const AnyComponent = () => {
    const [inputValue, setInputValue ] = React.useState('');
    
    const validateInput = () => {
      if(inputValue === "") alert("The input cannot be empty");
      else alert("All perfect!");
    };
    return <div>
        <input type="text" onChange={e => setInputValue(e.target.value)} value={inputValue} />
        <button onClick={validateInput}>Click to validate empty</button>
    </div>;
}

ReactDOM.render(
  <AnyComponent />,
  document.getElementById('container')
);