PropTypes - Runtime Type Checking for React Props

Updated Sep 07, 2021#react#libs#reviews

PropTypes was originally exposed as part of the React core module, and is commonly used with React components. You can use it to document the intended types of properties passed to components.

npm install --save prop-types

PropTypes exports a range of validators that can be used to make sure the data you receive is valid. When an invalid value is provided for a prop, a warning will be shown in the JavaScript console.

import React from 'react'
import PropTypes from 'prop-types'

class MyComponent extends React.Component {
  render() {
    // ... do things with the props

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.
  // see for more info
  optionalNode: PropTypes.node,

  // A React element (ie. <MyComponent />).
  optionalElement: PropTypes.element,

  // A React element type (eg. MyComponent).
  // a function, string, or "element-like" object (eg. React.Fragment, Suspense, etc.)
  // see
  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([

  // 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 (
  ) {
    if (!/matchme/.test(propValue[key])) {
      return new Error(
        'Invalid prop `' +
          propFullName +
          '` supplied to' +
          ' `' +
          componentName +
          '`. Validation failed.'

For performance reasons, propTypes is only checked in development mode.