Modular Node-

Modular

In order to resolve dependencies between files, modular specification is a good agreement.
The modular specification is a plain text of the agreement, the developers have to write code to the specifications, reduce communication costs, a great convenience to call each other between the modules.

First, understand CommonJS specification

1. Action: is a Javascript modular specification, the predetermined characteristics of the module and how the interdependence between the modules ;

2. Uses: Node.js CommonJS specifications are used;

3. Features: Synchronous load module; not suitable for use in the browser; browser using the AMD / CMD.

4. CommonJS specification defines what: Wiki description for Modules

4.1 如何引入 In a module, there is a free variable "require", that is a Function.
4.2 如何暴露给别人使用In a module, there is a free variable called "exports", that is an object that the module may add its API to as it executes.
4.3 必须有一个变量module 。In a module, there must be a free variable "module", that is an Object.

Second, the module scope and global scope

There are two scopes Node.js, are global scope and the module scope ;

1. Global scope: the use of global access, similar to the browser window ;
2. Each Javascript file is a separate module, each module has its own independent scope, therefore: the module members, the default can not be accessed by other modules.
3. Default Node, the method defined in each of the JS file, variables belong module scope.

Mount to global

var b = 20；
global.b = b； 
global.say = function () {
  console.log('这是挂载到全局的 say 方法')；
}

Reproduced in: https: //www.jianshu.com/p/6fb38b916cd9