环境检测:node.js 或浏览器

Fortunately there is a way of requiring the global scope and testing what it is - if you create a new function using a new Function() constructor, the execution scope of this is bound to the global scope and you can compare the global scope directly to the expected value. *)

所以要创建一个函数，检查全局范围是否为窗口"；会是

So to create a function check if the global scope is "window" would be

var isBrowser=new Function("try {return this===window;}catch(e){ return false;}");

// tests if global scope is bound to window
if(isBrowser()) console.log("running under browser");

以及测试全局范围是否绑定到全局"的函数.会是

And function to test if global scope is bound to "global" would be

var isNode=new Function("try {return this===global;}catch(e){return false;}");

// tests if global scope is bound to "global"
if(isNode()) console.log("running under node.js");

try...catch -part 将确保如果未定义变量，则返回 false.

the try... catch -part will makes sure that if variable is not defined, false is returned.

isNode() 还可以比较 this.process.title==="node" 或其他在 node.js 中找到的全局范围变量，如果你愿意的话，但在实践中与全局比较就足够了.

The isNode()could also compare this.process.title==="node" or some other global scope variable found inside node.js if you will, but comparing to the global should be enough in practice.

http://jsfiddle.net/p6yedbqk/

注意:不建议检测运行环境.但是，它在特定环境中可能很有用，例如在全球范围内具有一些已知特征的开发和测试环境.

NOTE: detecting the running environment is not recommended. However, it can be useful in a specific environment, like development and testing environment which has some known characteristics for the global scope.

现在 - 答案的第二部分. 环境检测完成后，您可以选择要使用哪个基于环境的策略(如果有)来绑定您的变量全球"到您的应用程序.

Now - the second part of the answer. after the environment detection has been done, you can select which environment based strategy you want to use (if any) to bind your variable which are "global" to your application.

在我看来，这里推荐的策略是使用单例模式将您的设置绑定到一个类中.SO中已经有一个很好的替代品列表

The recommended strategy here, in my opinion, would be to use a singleton pattern to bind your settings inside a class. There is a good list of alternatives already in SO

在 JavaScript 中实现单例的最简单/最干净的方法

因此，如果您不需要全局"；变量，您根本不需要环境检测，只需使用单例模式定义一个模块，该模块将为您存储值.好的，可以说模块本身是一个全局变量，在 JavaScript 中它实际上是一个全局变量，但至少在理论上它看起来更简洁一些.

So, it may turn out if you do not need a "global" variable, and you do not need the environment detection at all, just use the singleton pattern to defined a module, which will store the values for you. OK, one can argue that the module itself is a global variable, which in JavaScript it actually is, but at least in theory it looks a bit cleaner way of doing it.

*) https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function

注意:使用 Function 构造函数创建的函数不会创建关闭其创建上下文；它们总是在全球范围.运行它们时，它们将只能访问他们自己的局部变量和全局变量，而不是范围内的变量在其中调用了 Function 构造函数.

Note: Functions created with the Function constructor do not create closures to their creation contexts; they always are created in the global scope. When running them, they will only be able to access their own local variables and global ones, not the ones from the scope in which the Function constructor was called.

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