注意：React.PropTypes自从React v15.5以来，它已经进入了一个不同的包。请使用该prop-types库，而不是。我们提供了一个codemod脚本来自动化转换。

随着您的应用程序的增长，您可以通过类型检查来捕捉大量错误。对于某些应用程序，您可以使用JavaScript扩展（如Flow或TypeScript）来检查整个应用程序。但即使你不使用这些，React也有一些内置的类型检测功能。要在组件的道具上运行类型检查，可以指定特殊propTypes属性：

import PropTypes from 'prop-types'; class Greeting extends React.Component { render() { return ( 
Hello, {this.props.name}
 ); }} Greeting.propTypes = { name: PropTypes.string};

PropTypes导出一系列可用于确保您收到的数据有效的验证程序。在这个例子中，我们正在使用PropTypes.string。当为prop提供无效值时，JavaScript控制台中将显示警告。出于性能原因，propTypes仅在开发模式下进行检查。

PropTypes

这里是一个记录提供的不同验证器的例子：

import PropTypes from 'prop-types'; 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. optionalElement: PropTypes.element, // 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), // An object taking on a particular shape optionalObjectWithShape: PropTypes.shape({ color: PropTypes.string, fontSize: PropTypes.number }), // You can chain any of the above with `isRequired` to make sure a warning // is shown if the prop isn't provided. 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.' ); } })};

需要单个孩子

随着PropTypes.element您可以指定只有一个孩子可以传递给儿童一个组成部分。

import PropTypes from 'prop-types'; class MyComponent extends React.Component { render() { // This must be exactly one element or it will warn. const children = this.props.children; return ( 
 {children} 
 ); }} MyComponent.propTypes = { children: PropTypes.element.isRequired };

默认支柱值

您可以props通过分配特殊defaultProps属性来为您定义默认值：

class Greeting extends React.Component { render() { return ( 
Hello, {this.props.name}
 ); }} // Specifies the default values for props: Greeting.defaultProps = { name: 'Stranger'};// Renders "Hello, Stranger":ReactDOM.render( , document.getElementById('example'));

如果使用类似transform-class-properties的Babel变换，则还可以defaultProps在React组件类中声明为静态属性。尽管这个语法尚未完成，并且需要编译步骤才能在浏览器中工作。有关更多信息，请参阅班级字段提案。

class Greeting extends React.Component { static defaultProps = { name: 'stranger' } render() { return ( 
Hello, {this.props.name}
 ) }}

的defaultProps将被用于确保this.props.name，如果不是由父组件指定它将有一个值。类型检查propTypes发生在defaultProps解决后，因此类型检查也将适用于该类型defaultProps。