React手稿之類型檢查

tomorrowwu 發布于2019-08-26 12:24 / 3315人閱讀

摘要：類型檢查是為了確保傳入組件的參數正確性。通常在項目中可以使用或者來實現。示例以上內容在實現一個通用組件時非常有用。類型檢查和參數默認值一起使用，保證組件的正常運行。

Typechecking With PropTypes

類型檢查是為了確保傳入組件的參數正確性。

通常在項目中可以使用Flow或者TypeScript來實現。

React提供了PropTypes來檢查類型。

示例：

import PropTypes from "prop-types";

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

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 (
      
        {children}
      
    );
  }
}

MyComponent.propTypes = {
  children: PropTypes.element.isRequired
};

Default Prop Values

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")
);

以上內容在實現一個通用React組件時非常有用。類型檢查和參數默認值一起使用，保證組件的正常運行。