在JavaScript中添加全局变量/函数（特别是NativeScript） [英] Adding a global variable / function in JavaScript (specifically NativeScript)

问题描述

我正在学习如何使用NativeScript编写应用程序。我相信最好的学习方法就是做。出于这个原因，我正在构建一个基本的应用程序。

I'm learning how to write apps with NativeScript. I believe the best way to learn is by doing. For that reason, I'm building a basic app.

在这个应用程序中，我正在尝试创建一个函数和一个变量，我可以访问所有视图模型和应用程序中的其他代码。为了做到这一点，我想我会在应用程序对象上添加一个函数和变量。

In this app, I'm trying to create a function and a variable that I can access across ALL of the view models and other code in the app. In an attempt to do this, I thought I would add a function and variable on the application object.

在NativeScript中，使用以下代码初始化应用程序：

In NativeScript, the app is initialized using the following code:

app.js

var application = require("application");
application.mainModule = "main-page";
application.start();

我想我可以捎带这个并添加一个全局可见的函数和变量，如下所示：

I figured I could piggy back on this and add a globally visible function and variable like so:

application.prototype.myFunction = function() {
  console.log('I made it!');
};
application.myVariable = 'some value';

然后，在我的视图模型或其他代码中，我可以执行以下操作：

Then, in my view models, or other code, I could just do something like the following:

views / home.js

application.myFunction();
console.log(application.myVariable);

但是，当我运行此代码时，我收到一条错误消息，指出该应用程序未定义。我不完全理解这一点。我认为，因为应用程序在app.js中定义/实例化，它将全局可见。但是，它似乎不是。与此同时，我不知道该怎么做。

However, when I run this code, I get an error that says that application is undefined. I do not fully understand this. I thought that because application is defined/instantiated in app.js that it would be globally visible. However, it does not seem to be. At the same time, I'm not sure what to do.

推荐答案

使用全局命名空间。在您的 app.js 中，代码：

Use the global namespace. In your app.js, code:

var application = require("application");
application.mainModule = "main-page";

global.myVariable = 'some value';

application.start();

然后，您可以在应用中的任何位置使用 global.myVariable 。

You can then use global.myVariable anywhere in your app.

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