How can I use Global Variables in Node.js?

Accessing Global Variables in Node.js

In Node.js, global variables are accessible from any file in the application. However, there are certain nuances to consider when setting and using global variables.

Assigning to the Global Scope Without the var Keyword

As mentioned in the question, setting a variable without the var keyword does not automatically place it in the global scope. This is because Node.js uses a lexical scoping mechanism where variables are scoped to the block in which they are defined.

Using global Object

To assign a variable to the global scope, the global object can be used. The global object is a reference to the global namespace and is available in all contexts. By assigning a variable to the global object, it becomes accessible as a global variable.

Example:

<code class="javascript">global._ = require('underscore');</code>

Using app.set in Express.js

Express.js provides a convenient method for setting and getting values that are shared across multiple modules and routes. The app.set function allows you to set a value to a specific key in the application's settings. These settings are accessible through the app.get function anywhere in the application.

Example:

<code class="javascript">app.set('myGlobalVar', 'Some value');</code>

Accessing Global Variables

To access a global variable, you can simply use the variable name. In the example above, the global variable _ can be used in any file by writing:

<code class="javascript">_.each([1, 2, 3], function(val) { /* Do something */ });</code>

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