NodeJS / Typescript导出/导入的正确解释？ [英] Proper explanation for NodeJS/Typescript Export / Import?

问题描述

有人可以使用Typescript准确解释导出和导入在NodeJS中的工作原理吗？

我的设置是：

• NodeJS


• 打字稿中的所有内容


• TSLint


• 打字

我正在搞乱出口/进口，而不是做一些正确的编码，它让我疯狂，并且找不到任何正确的解释它是如何工作的。

导入

您能否解释以下内容：

  var module = require（module）; 
 
 import module = require（module）;来自module的
 
导入模块; 
 
从模块导入{something}; 
 
 import *作为模块来自module; 
  

导出

<你能解释一下吗？

  export = something; 
 
导出默认值; 
 
导出界面| class something; 
  

问题

• 如何在不启动类的情况下正确导出/导入类


• 如何在启动/导入类的情况下正确导出/导入类（构造确实运行）


• 如何正确导出/导入类和接口


• 如何正确导出/导入类和多个接口


• 什么时候使用模块声明，如果我尝试使用它们，为什么tslint会向我抛出错误。

我似乎无法找到正确的导出与导入的方法，因此我的IDE不会被红色覆盖并向我抛出数百个错误。

一般问题

• 有没有办法不使用nodejs / typescript / tslint获取错误？


• TSLint正在为我几乎所有打字的东西尖叫......这是非常令人沮丧的，因为大多数错误都有0个解释ORS。是否值得使用它？

问题列表一直在继续，但我确定一旦上面的一些问题得到解答，我可以接受其余的。

谢谢你，对不起这样的一般性问题，但我的挫折程度刚刚达到顶峰......

解决方案

同意，导入/导出语法至少有两个原因令人困惑：

• commonjs语法： var module = require（module）; 有效，但这是commonjs - > no typings


• 它发生了变化：语法 import x = require（'y'）现已弃用于TS

TL; DR; ：使用TS 1.5中引入的'es6 style'语法

'最佳'资源在TS中导入/导出我知道是这个

总的来说，我建议阅读此内容优秀的手册，它将为您的大多数问题提供答案

要导入

从默认导出

某物被导出为默认（单个）导出，即导出默认值 in ts / es6

使用

  import模块中的东西
  

您实际上可以导入具有不同名称的默认导出。 从'module'导入SomethingElse也可以使用

来自命名导出

使用 export {Something} 导出为module中的命名导出c $ c>或导出类|接口在ts / es6中的东西{}

你想只导入那个，使用

 从模块导入{Something} 
  

您想导入从名称空间 mod

下的module导出的所有内容

  import * as mod frommodule 
  

然后使用 const c：mod.Something = whatever

要导出

参见上面的 import

表单 export = something不推荐使用来支持新的ES6样式语法。它主要在定义文件中找到，表示js库导出单个函数/对象e。 g。 module.exports =某事。

你应该尝试使用什么

使用ES6样式语法并避免默认导出：它们的优点是可以使用不同的名称导入它们，但

• 无法重新导出默认导入，如果您正在编写库，这可能会有问题


• 他们会混淆很多重构时的IDE（更不用说你自己）


• 命名导出实际上可以在导入时进行本地重命名，即从模块导入{Something as SomethingElse}

具体而言，出口任何需要出口的东西并专门导入

在 api.ts

 导出界面MyInterface {
} 
 
导出类MyClass {
} 
  

在 main.ts

 从'导入{MyInterface，MyClass}。 / api'
  

Linting

有很多优秀的IDE提供优秀的linting：VSCode，Atom Typescript和Webstorm命名一个受欢迎的少数人，前两个是免费的，第三个甚至为你管理进口。

Could someone please explain exactly how exports and imports work in NodeJS using Typescript?

My setup is:

• NodeJS
• Everything in Typescript
• TSLint
• Typings

I am messing about with exports/imports instead of doing some proper coding, its driving me nuts, and cannot find any proper explanation of how it works.

Import

Can you please explain following:

var module = require ("module");

import module = require("module");

import module from "module";

import {something} from "module";

import * as module from "module";

Export

Can you please explain following

export = something;

export default something;

export interface|class something;

Questions

• How do properly export/import a class without initiating it
• How do properly export/import a class with it being initiated (construct did run)
• How do I properly export/import a class and interface
• How do I properly export/import class and multiple interfaces
• When to use modules declarations, what are they good for and why is tslint throwing errors at me if I try to use them.

I cannot seem to find proper way of doing exports vs. imports so my IDE is not covered in red and throwing hundreds of errors at me.

General Questions

• Is there even a way to not get errors using nodejs/typescript/tslint?
• TSLint is screaming at me for almost anything I type... it is extremely frustrating since there is 0 explanation to most of the errors. Is it even worth using it?

List of questions goes on and on, but im sure once some of the above is answered, I can pick up on the rest.

Thank you and sorry for such a general question, but my frustration level just reached the top...

解决方案

Agreed, import/export syntax is confusing for at least two reasons:

• the commonjs syntax: var module = require ("module"); works but that is commonjs -> no typings
• it changed: the syntax import x = require('y') is now deprecated in TS

TL;DR;: Use the 'es6 style' syntax introduced in TS 1.5

The 'best' resource on import/export in TS I know is this

Overall I recommend reading this excellent handbook which will provide answers to most of your questions

To import

From a default export

Something was exported as a default (single) export ie export default Something in ts/es6

Use

import Something from "module"

You can actually import a default export with a different name. import SomethingElse from 'module' will also work

From named exports

Something was exported as a named export in "module" using export {Something} or export class|interface Something{} in ts/es6

You want to import only that, use

import {Something} from "module"    

You want to import everything that is exported from "module" under the namespace mod

import * as mod from "module

Then use const c:mod.Something = whatever

To export

See imports above

The form export = something is deprecated in favor of the new ES6 style syntax. It is mostly found in definition files to express the fact that a js library exports a single function/object e.g. module.exports=something.

What you should try using

Use ES6 style syntax and avoid default exports: they have the advantage that they can be imported using a different name but

• a default import cannot be re-exported, which may be problematic if you are writing a library
• they will confuse a lot of IDEs (not to mention yourself) when refactoring
• a named export can actually be locally renamed when imported i.e. import {Something as SomethingElse} from "module"

Concretely, export whatever needs to be exported and import it specifically

In api.ts

export interface MyInterface {
}

export class MyClass {
}

In main.ts

 import {MyInterface, MyClass} from './api'

Linting

There are a lot of good IDEs out there that provide excellent linting: VSCode, Atom Typescript and Webstorm to name a popular few, the first two being free and the third one even manages the imports for you.

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