React手稿之类型检查

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Typechecking With PropTypes
类型检查是为了确保传入组件的参数正确性。
通常在项目中可以使用 Flow 或者 TypeScript 来实现。
React 提供了 PropTypes 来检查类型。
示例：
import PropTypes from ‘prop-types’;

class Greeting extends React.Component {
render() {
return (
<h1>Hello, {this.props.name}</h1>
);
}
}

Greeting.propTypes = {
name: PropTypes.string
};
PropTypes
import PropTypes from ‘prop-types’;

MyComponent.propTypes = {
// You can declare that a prop is a specific JS type. 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.’
);
}
})
};
Requiring Single Child
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 (
<div>
{children}
</div>
);
}
}

MyComponent.propTypes = {
children: PropTypes.element.isRequired
};
Default Prop Values
class Greeting extends React.Component {
render() {
return (
<h1>Hello, {this.props.name}</h1>
);
}
}

// Specifies the default values for props:
Greeting.defaultProps = {
name: ‘Stranger’
};

// Renders “Hello, Stranger”:
ReactDOM.render(
<Greeting />,
document.getElementById(‘example’)
);
以上内容在实现一个通用 React 组件时非常有用。类型检查和参数默认值一起使用，保证组件的正常运行。
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