In this lesson we'll learn about how you can use the prop-types module to validate a custom React component's props.
You can write you own PropTypes vlidators like such:
const PropTypes = { string(props, propName, componentName) { if(typeof props[propName] !== 'string') { return new Error( `You should pass a string for ${propName} but you pass ${typeof props[propName]}` ) } } }
Because this is commonly used, so we can use React libs for that:
https://www.npmjs.com/package/prop-types
<body> <script src="https://unpkg.com/react@16.0.0/umd/react.development.js"></script> <script src="https://unpkg.com/react-dom@16.0.0/umd/react-dom.development.js"></script> <script src="https://unpkg.com/prop-types@15.6.0/prop-types.js"></script> <script src="https://unpkg.com/babel-standalone@6.26.0/babel.js"></script> <div id="root"></div> <script type="text/babel"> class SayHello extends React.Component { static propTypes = { firstName: PropTypes.string.isRequired, lastName: PropTypes.string.isRequired, } render() { return ( <div> Hello {this.props.firstName} {this.props.lastName}! </div> ) } } ReactDOM.render( <SayHello firstName={true} />, document.getElementById('root') ) </script> </body>
For producation, PropTypes is not necessary, and will slow down the proferemence, so we can remove it by using the babel plugin:
https://www.npmjs.com/package/babel-plugin-transform-react-remove-prop-types