且构网

分享程序员开发的那些事...
且构网 - 分享程序员编程开发的那些事

ES6结构和模块导入

更新时间:2022-11-02 19:37:00

  import'link'from'react-router'; 

反应路由器导入名为export 的 ,即像

  export const Link = 42; 






  import路由器从反应路由器; 
const {Link} =路由器;

链接 strong> default export ,假设它是一个对象,例如

  export default {
链接:42
};

(默认导出实际上只是一个名为default的标准化命名导出) / p>

另请参见 export 在MDN上



完整示例:

  // react-router.js 
export const Link = 42;
export default {
链接:21,
};


// something.js
import {Link} from'./react-router';
import''./react-router'的路由器;
const {Link:Link2} =路由器;

console.log(Link); // 42
console.log(Link2); // 21






与Babel 5及以下我相信它们是可互换的,因为ES6模块已经被泛化到CommonJS。但是就语言而言,这是两种不同的结构。


I was under the impression that this syntax:

import Router from 'react-router';
var {Link} = Router;

has the same final result as this:

import {Link} from 'react-router';

Can someone explain what the difference is?

(I originally thought it was a React Router Bug.)

import {Link} from 'react-router';

imports a named export from react-router, i.e. something like

export const Link = 42;


import Router from 'react-router';
const {Link} = Router;

pulls out the property Link from the default export, assuming it is an object, e.g.

export default {
  Link: 42
};

(the default export is actually nothing but a standardized named export with the name "default").

See also export on MDN.

Complete example:

// react-router.js
export const Link = 42;
export default {
  Link: 21,
};


// something.js
import {Link} from './react-router';
import Router from './react-router';
const {Link: Link2} = Router;

console.log(Link); // 42
console.log(Link2); // 21


With Babel 5 and below I believe they have been interchangeable because of the way ES6 modules have been transpiled to CommonJS. But those are two different constructs as far as the language goes.