Posted in react
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4:40 am, October 19, 2021

How to Use PropTypes to Define Props in React

React allows you to define the types of props given to your components to make sure that invalid data is not sent as the prop to the element. 

To do this you can define propTypes.

You can define propTypes the same way that you define defaultProps.

Here is a list of other proptypes available to check and as of 15.5 these ones

Javascript

MyComponent.propTypes = {
  // You can declare that a prop is a specific JS primitive. By default, these
  // are all optional.
  optionalArray: PropTypes.array,
  optionalBool: PropTypes.bool,
  optionalFunc: PropTypes.func,
  optionalNumber: PropTypes.number,
  optionalObject: PropTypes.object,
  optionalString: PropTypes.string,
  optionalSymbol: PropTypes.symbol,
 
  // Anything that can be rendered: numbers, strings, elements or an array
  // (or fragment) containing these types.
  optionalNode: PropTypes.node,
 
  // A React element (ie. <MyComponent />).
  optionalElement: PropTypes.element,
 
  // A React element type (ie. MyComponent).
  optionalElementType: PropTypes.elementType,
 
  // You can also declare that a prop is an instance of a class. This uses
  // JS's instanceof operator.
  optionalMessage: PropTypes.instanceOf(Message),
 
  // You can ensure that your prop is limited to specific values by treating
  // it as an enum.
  optionalEnum: PropTypes.oneOf(['News', 'Photos']),
 
  // An object that could be one of many types
  optionalUnion: PropTypes.oneOfType([
    PropTypes.string,
    PropTypes.number,
    PropTypes.instanceOf(Message)
  ]),
 
  // An array of a certain type
  optionalArrayOf: PropTypes.arrayOf(PropTypes.number),
 
  // An object with property values of a certain type
  optionalObjectOf: PropTypes.objectOf(PropTypes.number),
 
  // You can chain any of the above with `isRequired` to make sure a warning
  // is shown if the prop isn't provided.
 
  // An object taking on a particular shape
  optionalObjectWithShape: PropTypes.shape({
    optionalProperty: PropTypes.string,
    requiredProperty: PropTypes.number.isRequired
  }),
 
  // An object with warnings on extra properties
  optionalObjectWithStrictShape: PropTypes.exact({
    optionalProperty: PropTypes.string,
    requiredProperty: PropTypes.number.isRequired
  }),
 
  requiredFunc: PropTypes.func.isRequired,
 
  // A value of any data type
  requiredAny: PropTypes.any.isRequired,
 
  // You can also specify a custom validator. It should return an Error
  // object if the validation fails. Don't `console.warn` or throw, as this
  // won't work inside `oneOfType`.
  customProp: function(props, propName, componentName) {
    if (!/matchme/.test(props[propName])) {
      return new Error(
        'Invalid prop `' + propName + '` supplied to' +
        ' `' + componentName + '`. Validation failed.'
      );
    }
  },
 
  // You can also supply a custom validator to `arrayOf` and `objectOf`.
  // It should return an Error object if the validation fails. The validator
  // will be called for each key in the array or object. The first two
  // arguments of the validator are the array or object itself, and the
  // current item's key.
  customArrayProp: PropTypes.arrayOf(function(propValue, key, componentName, location, propFullName) {
    if (!/matchme/.test(propValue[key])) {
      return new Error(
        'Invalid prop `' + propFullName + '` supplied to' +
        ' `' + componentName + '`. Validation failed.'
      );
    }
  })
};

 

HTML

<div id="challenge-node"></div>

Scripts

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/18.0.0-alpha-5fa4d79b0-20211008/umd/react.production.min.js" integrity="sha512-5PVmWGoNJocWPdQJmJd1aRbz3cFcFgXctWKLWcitqtgX64jF+ttfg9g2oLltmeQ1HUo3gT6QchaMK3h+S+JG4Q==" crossorigin="anonymous"
  referrerpolicy="no-referrer"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/18.0.0-alpha-5fa4d79b0-20211008/umd/react-dom.production.min.js" integrity="sha512-pUsjUv+9XgkTn+UbLyNIT4YNZPF2p0E45FBKmDL7Ti8iovYwp2CUkQs6Q7J9y5scLxWaOM+T5jJc0ls+WHUcmQ=="
  crossorigin="anonymous" referrerpolicy="no-referrer"></script>
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
<script type="text/babel">
const Items = (props) => {
  return <h1>Current Quantity of Items in Cart: {props.quantity}</h1>
};

// Change code below this line
Items.propTypes = { quantity: PropTypes.number.isRequired }
// Change code above this line

Items.defaultProps = {
  quantity: 0
};

class ShoppingCart extends React.Component {
  constructor(props) {
    super(props);
  }
  render() {
    return <Items />
  }
};
ReactDOM.render(<ShoppingCart />, document.getElementById('challenge-node'));</script>

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