Javascript，将属性推送到父级范围

Question

我正在构建一些 node.js 模块，并且我想将一些库推送到这个对象中

在这个场景中，我有

app.js

var api = require('./scripts/api.js');
var oauth = require('./scripts/oauth.js');
var db = require('./scripts/db.js')
var libraries  = {
    api : api,
    db : db,
    oauth : oauth,
}

var modules = require('./scripts/module.js');
modules.init(app, libraries);

模块.js

module.exports = { 

    init : function(app,libraries) {
        for (key in libraries) {
            if (libraries.hasOwnProperty(key)) {
                this[key] = libraries[key]
            }
        }

        this.oauth.init(app,libraries);
    }
}

api.js

module.exports = { 

init : function(app, libraries) {
    for (key in libraries) {
        if (libraries.hasOwnProperty(key)) {
            this[key] = libraries[key]
        }
    }
    app.get('/api/linkedin/posts', function (req, res) {

        //get the credentials
        var userid = req.session.user_id;
        var credentials = '';
        getCredentials('linkedin',userid)
            .then(function(result) {
                this.db.store(credentials = JSON.parse(result))
                    })
    });
}, 
}

它工作正常，但是我希望发生的不是将它推到模块对象本身上。将其推送到对象范围，这样我就不必将 this.library.function() 添加到所有内容中。这样我就可以直接调用 oauth.init() 访问库了，有什么好的方法吗？

我想要完成的是产生与我执行以下操作相同的效果，我只是想让这些引导方法变得神奇

模块.js

var api = {}
var oauth = {}

module.exports = { 

    init : function(app,libraries) {
        api = libraries.api
        oauth = libraries.oauth

        oauth.init(app,libraries);
    }
}

这是一个演示问题的小提琴http://jsbin.com/cadejukijudu/1/edit

Answer 1

@Matthew Bucci：你的问题让我很困惑——不是因为你的编码风格，而是因为问题的描述和程序设计——所以我开始稍微重写你的问题并添加 cmets .希望问题及其答案将变得显而易见；如果不是我，那就是别人。

---

您的问题：

App.js

var libraries = {
    "api": require('./scripts/api.js'),
    "db": require('./scripts/db.js'),
    "oauth": require('./scripts/oauth.js')
};

var modules = require('./scripts/module.js');
modules.init(app, libraries);
// Where does the app variable come from?
// The naming of your script "module.js" is confusing,
// because node has a built-in module called module...

Module.js

module.exports = {
    "init": function (app, libraries) {
        var key;
        for (key in libraries) {
            if (libraries.hasOwnProperty(key)) {
                this[key] = libraries[key];
                // So you effectively want to copy all properties of libraries
                // to the object in the variable modules in app.js?
            }
        }
        this.oauth.init(app, libraries);
        // I assume the oauth object, required in app.js, also has an init property.
        // So you effectively want to copy all properties of libraries to the modules
        // object and to the oauth object contained in the modules object!?
        // Just pointing out, you're using the same app variable passed in app.js,
        // which in this context is an argument of the module.js .init function.
    }
};

api.js 等等

---

猜测答案：

init.js

global.api = require('./scripts/api.js');
global.oauth = require('./scripts/oauth.js');
global.db = require('./scripts/db.js');
// Any initialization of required objects is best done when the respective code is
// evaluated, i.e. the first time they're required; Initialization code should be 
// included in respective modules.

app.js

api; // Not available yet!
require('./scripts/init.js');
api; // Refers to the result of require('./scripts/api.js') initialized in init.js
oauth; // idem, etc.

---

总结：我认为你正在处理一个你不应该处理的问题。对象没有作用域，也没有父对象。对象嵌套形成的属性树是单向的，因为一个对象可以是多个其他对象的属性；所以一般来说，从嵌套对象中检索对嵌套对象的引用是非常不可行的；它需要您编写一个非常精细的搜索函数，执行起来会非常昂贵。如果您想将一个对象的属性复制（推送）到另一个对象 - 无论一个对象是否嵌套在另一个对象中 - 只需制作一个通用的复制功能；您必须明确告诉函数需要将什么复制到什么上。

函数有范围，使用 let 语句块语句可以有范围。对象的花括号不是块语句。

Answer 2

我发现我可以通过在不带 var 关键字的 init 函数中声明它来强制它工作，假设范围是 GLOBAL，这是一种糟糕的做法

http://jsfiddle.net/4wjbyy9g/6/

  this.init = function(libraries)
  {
     for (var key in libraries) {
        var messy = key + " = libraries[key] "

        eval(messy)
     }
     oauth.log('yay!');
  };

可以通过在模块中手动声明变量来避免全局范围问题，但这并不像我想要的那样干净，因为我必须手动声明每个变量名。然而，这是迄今为止我发现的最干净的解决方案

function module()
{
  var oauth = {} //I don't want to have to write this to keep it out of the global scope

  this.init = function(libraries) {
     for (var key in libraries) {
        var messy = "if (typeof " + key + " !== 'undefined') {"
        messy += key + " = libraries[key] }"

        eval(messy)
     }
     oauth.log('yay!');
  }

  this.test = function() {
     oauth.log(JSON.stringify(oauth))     
  }
}

http://jsfiddle.net/52ea5t0q/6/