在React Native中声明全局类变量

// global.js
global.myVariable = 'Hello World';

// 在其他文件中使用
import React from 'react';

console.log(global.myVariable); // 输出 'Hello World'

// MyContext.js
import React from 'react';

const MyContext = React.createContext();

export default MyContext;

// App.js
import React from 'react';
import MyContext from './MyContext';

class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      myVariable: 'Hello World',
    };
  }

  render() {
    return (
      <MyContext.Provider value={this.state.myVariable}>
        {/* 其他组件 */}
      </MyContext.Provider>
    );
  }
}

export default App;

// MyComponent.js
import React from 'react';
import MyContext from './MyContext';

class MyComponent extends React.Component {
  render() {
    return (
      <MyContext.Consumer>
        {value => <Text>{value}</Text>}
      </MyContext.Consumer>
    );
  }
}

export default MyComponent;