Coffeescript 和 node.js 混淆.需要实例化类? [英] Coffeescript and node.js confusion. require instantiates class?

问题描述

我在尝试让我的类在我的 node.js 文件中工作时遇到问题.当我需要我编写的模块时，require './module' 调用我的构造函数并给出错误.但我实际上想稍后在文件中实例化.

I'm having trouble trying to get my class working in my node.js file. When I require the module I wrote, the require './module' calls my constructor and gives an error. But I actually want to instantiate later on in the file.

即

class Mic

constructor: (x) ->
  @t = []
  @t.push x

exports.Mic = Mic

这是我的 app.coffee 文件

and here is my app.coffee file

require 'coffee-script'
require './Mic'

当我运行 app.coffee 时，它​​会给出异常 ReferenceError: x is not defined.这是有道理的，因为它调用了构造函数，但是为什么即使我没有调用 new Mic 也调用构造函数?

When I run app.coffee it gives an exception ReferenceError: x is not defined. Which makes sense since its calling the constructor, but why is it calling the constructor even though I havent called new Mic ?

编辑固定缩进后

class Mic
    constructor: (x) ->
        @t = []
        @t.push x

exports.Mic = Mic

并将我的 app.coffee 更新为

and updating my app.coffee to

Mic = require './Mic'

m = new Mic 3
console.log m

我得到了错误

TypeError: object is not a function
    at Object.CALL_NON_FUNCTION_AS_CONSTRUCTOR (native)

推荐答案

第一件事:你不需要 require 'coffee-script'——用 coffee 运行它代码>就足够了；与运行已编译的 JavaScript 相同.您不需要程序运行时可用的 CoffeeScript 库.

First thing's first: you don't need the require 'coffee-script'—running it with coffee is enough; same as running the compiled JavaScript. You don't need the CoffeeScript library available at runtime in your program.

其次，第一个文件出现缩进错误；如果你想让它成为 Mic 的构造函数，在 class 下缩进一层，即:

Secondly, the first file appears indented incorrectly; if you want that to be Mic's constructor, indent it one level underneath the class, i.e.:

class Mic
  constructor: (x) ->
    @t = []
    @t.push x

exports.Mic = Mic

最后，问题在于 exports 是导出的 object.见这里:

Finally, the issue is that exports is an object of exports. See here:

exports.Mic = Mic

您已将 Mic 分配给 exports 对象的 Mic 键，所以现在在 Mic.coffee 中 exports看起来像这样:

You've assigned Mic to the exports object's Mic key, so now exports in Mic.coffee looks like this:

{ Mic: ...your class... }

当您说 require './Mic' 时，您将获得该对象；换句话说:

When you say require './Mic', you're getting that object back; in other words:

require('./Mic') == { Mic: ...your class... }

因此您需要执行以下操作之一:

So you need to do one of the following:

1. 将 Mic 导出为 Mic.coffee 的整个导出，而不是键:

1. Export Mic as the entire export of Mic.coffee, and not as a key:

module.exports = Mic

把整个模块拿出来，然后在里面实例化Mic对象:

mic = require './Mic'
m = new mic.Mic 3

只需从 require 的模块中取出 Mic:

{Mic} = require './Mic'  # equivalent to saying Mic = require('./Mic').Mic
m = new Mic 3

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