Register Helper函数Node.JS Express

我正在尝试学习NodeJS和Express.我使用node-localstorage包来访问localstorage.这在直接在这样的函数中使用代码时有效

路线/ social.js

exports.index = function(req,res)
{
     if (typeof localStorage === "undefined" || localStorage === null) 
     {
        var LocalStorage = require('node-localstorage').LocalStorage;
        localStorage = new LocalStorage('./scratch');
     }

localStorage.setItem('myFirstKey','myFirstValue');
console.log(localStorage.getItem('myFirstKey'));
res.render('social/index',{title: "Start"});
}

但是,在访问localstorage时,我不想在所有其他函数中反复编写此代码.我希望能够注册一个我可以访问的辅助函数

var localStorage = helpers.getLocalStorage

或类似的东西.

我怎样才能在NodeJS中做到这一点？我见过关于app.locals的一些事情？但是如何在路线中访问app对象？

解决方法

有很多方法可以执行此操作,具体取决于您计划使用辅助方法的方式/位置.我个人更喜欢用我需要的所有帮助器和实用程序方法设置我自己的node_modules文件夹,名为utils.

例如,假设以下项目结构：

app.js
db.js
package.json
views/
   index.ejs
   ...
routes/
   index.js
   ...
node_modules/
   express/
   ...

只需在node_modules下添加一个utils文件夹,其中包含一个index.js文件,其中包含：

function getLocalStorage(firstValue){
   if (typeof localStorage === "undefined" || localStorage === null) 
   {
      var LocalStorage = require('node-localstorage').LocalStorage;
      localStorage = new LocalStorage('./scratch');
   }
   localStorage.setItem('myFirstKey','myFirstValue');
   return localStorage;
}
exports.getLocalStorage = getLocalStorage;

然后,只要您需要此功能,只需要模块utils：

var helpers = require('utils');
exports.index = function(req,res){
  localStorage = helpers.getLocalStorage('firstValue');
  res.render('social/index',{title: "Start"});
}

编辑
正如Sean在评论中所指出的,只要您将node_modules文件夹命名为不同于Node’s core modules的名称,此方法就可以工作.这是因为：

Core modules are always preferentially loaded if their identifier is passed to require(). For instance,require(‘http’) will always return the built in HTTP module,even if there is a file by that name.