1 React Native里面一般导出函数或者常量或者组件
如果是默认组件或者类(export default修饰)的话,在另外一个地方导入的时候不需要加上{},格式如下
导出
1. export default class Student { 2. }
导入
import Student from "./file"
如果不是默认组件或类或则方法或则变量(没有用default修饰)的话,在另外一个地方导入的时候需要加上{},格式如下
导出:使用module.exports
module.exports = {fun1, fun2, 常量}
导入
import {xxx2, xxx2, ...} from "./file"
好处:在另外一个文件地方导入了,就可以使用导入的函数或者变量或者组件,非常方便,相当于java里面的import导入类文件一样.
还可以是用一个变量,然后变量里面放键值对数组,key是函数名字,value是函数实现
如下
let fun = {fun1 : (a, b) => {return a + b}, fun2 : (a, b) => {return a - b}} export default fun;
2 简单测试
Student.js文件如下
'use strict'; import React from 'react' class Student { constructor(name: string) { this.name = name; } _getName = () => { console.log("_getName"); return this.name; }; } export default Student
Fun.js文件如下
'use strict'; import React from 'react' const sum = (a, b) => { return a + b; } const sub = (a, b) => { return a - b; } const myName = 'chenyu'; module.exports = { sum, sub, myName }
Fun_second.js文件如下
'use strict'; import React from 'react' //我们把所有的函数放在一个变量里面,这个变量里面放的都是键值对, //然后key是函数名字,value是我们函数实现 let fun = { //记得这是是let fun = { },不是let fun {} //相加函数 sum : (a, b) => { return a + b; }, //相减函数 sub : (a, b) => { return a - b; } } export default fun;
App.js文件如下
import React from 'react'; import {View, Text} from 'react-native'; import {DeviceEventEmitter} from "react-native"; import Student from "./Student" import {sub, sum, myName} from "./Fun" import fun from "./Fun_second" export default class App extends React.Component { constructor(props) { super(props); this.state = { name: '点击我', sumRes: 'sumRes', subRes: 'subRes', stuName: 'hello', sumRes_sec: 'sumRes_sec', subRes_: 'subRes_' }; } render() { return ( <View style={{flex: 1, alignItems: 'center', justifyContent: 'center'}}> <Text onPress={() => this._press(5, 2)} >{this.state.name}</Text> <Text>{this.state.sumRes}</Text> <Text>{this.state.subRes}</Text> <Text>{this.state.stuName}</Text> <Text>{this.state.sumRes_sec}</Text> <Text>{this.state.subRes_}</Text> </View> ); } _press = (a, b) => { this.setState({name: myName}); let res = sum(a, b); console.log("res is:" + res); this.setState({sumRes : res}); let res1 = sub(a, b); console.log("res1 is:" + res1); this.setState({subRes : res1}); let student = new Student("chengongyu"); let studentName = student._getName(); this.setState({stuName : studentName}); let sumSec = fun.sum(4, 9); this.setState({sumRes_sec : sumSec}); let subSec = fun.sub(10, 2); this.setState({subRes_: subSec}); } }
3 运行结果
