CommonJS Modules - 导出一个返回带参数的函数的函数

In this rendr - sessions example, there's an express middleware module...

在这个rendr - sessions示例中,有一个快速的中间件模块......

module.exports = function incrementCounter() {
  return function incrementCounter(req, res, next) {
    var app = req.rendrApp
      , count = app.get('session').count || 0;
    req.updateSession('count', count + 1);
    next();
  };
};

Can you not achieve the same thing with the following?

以下是否可以达到同样的目的?

module.exports = function incrementCounter(req, res, next) {
  var app = req.rendrAp
  , count = app.get('session').count || 0;
  req.updateSession('count', count + 1);
  next();
};

My Question is, why would you export a function which returns a function with arguments? Is there some sort of benefit to the former that I am unaware of?

我的问题是,为什么要导出一个返回带参数函数的函数?我不知道前者会有某些好处吗?

1 个解决方案

#1

rendr uses Express-style middleware.

rendr使用Express风格的中间件。

By convention, third-party middleware in Express are not provided as the actual middleware. Instead, they are provided as functions that create the middleware based on an options object parameter.

按照惯例,Express中的第三方中间件不作为实际的中间件提供。相反,它们是作为基于选项对象参数创建中间件的函数提供的。

However, since there are no options to be provided here, it is omitted.

但是,由于此处没有提供选项,因此省略。

But still, in order to follow the conventions of the surrounding library, it needs to be a factory function that returns a middleware function. So that's why it is wrapped up that way here.

但是,为了遵循周围库的约定,它需要是一个返回中间件函数的工厂函数。所以这就是为什么它在这里被包裹起来的原因。

#1