ES6 modularization

1.node.js How to realize modular specification in

node.js Followed CommonJS Modular specification of .

Import other modules to use require() Method .

Modules are shared externally as module.exports object .

2. The benefits of modularity

Everyone follows the same modular specification to write code , Reduce the cost of communication , It's very convenient for each module to call each other .

3. Classification of front-end modular specifications

    stay es6 Before modularity was born ,JavaScript Community is used AMD、CMD、CommonJS Isomodular specification .

AMD、CMD Suitable for browser side .

CommonJS Applicable to server side .

Most modular specifications increase the difficulty of learning and the cost of development for developers . therefore ,es6 The module specification was born .

4.es6 Modular specification ： It is a general modular development standard for browser and server .

es6 It is defined in the modular specification ：

Every js File is a separate module .

Import other module members to use import keyword .

Shared module members use export keyword .

 stay node.js Chinese support CommonJS Modular specification , If you want to be based on node.js Study es6 Modular Syntax , You can configure it in the following two steps ：

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stay package.json Add... To the root node of ”type”:”module” node .

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Quickly initialize a package management configuration file -package.json The order of ：

npm init -y

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Commands can be carried out at the code terminal , If there are questions , Environment variables can be configured .

5.es6 The basic syntax of modularity ： Yes 3 Grammar .

Default export and default import

Default export Syntax ：export default { Default exported members （ Variables or functions ） }

     matters needing attention ： Use only once in each module export default, Otherwise, an error will be reported .

Default import Syntax ：import Accept name from ‘ Module identifier ’

Example ：import m1 from ./out.js

     matters needing attention ： Accept the name as long as it is legal .
     matters needing attention ： When the terminal writes a command , If appear module Problems that can't be found , Then it depends on whether there is a problem with the path .

cd Path address → You can switch paths

cls → eliminate

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On demand export and on demand import

Export syntax on demand ：export Members exported on demand

Import grammar on demand ：import { s1 } from ‘ Module identifier ’

matters needing attention ： If there are multiple member variables , Just separate them with commas .

Multiple on-demand exports can be used in each module .

The name of on-demand import is consistent with that of on-demand Export .

On demand import , have access to as Keyword to rename .

On demand import can be used with default Export .

Directly import and execute the code in the module

grammar ：import ‘./direct-run.js’