Node.js dependency management that 90% of people don't know (Part 2)

Grape City technical team 2021-06-18 12:11:46
node.js node js dependency management


Reprint please indicate the source : Grape city official website , Grape city provides professional development tools for developers 、 Solutions and services , Enabling developers .
Original reference :https://dzone.com/articles/node-dependency-management-part2

I'll introduce you to Node.js In the article of dependency management , We introduced about Node.js Basic knowledge of modules , How to use module.exports and require Method to handle dependencies , And folder dependencies (folder dependencies) How it works and how it works .

Today we will continue to start from that , To learn how to use this system module to break down an application into multiple modules , And the advantages and Node.js How it works .

In this article, I mentioned some experience sharing in the first part , Before reading this article, you can read the first part to learn more about .

Before we start learning how to set up an application using multiple modules , Let's get to know Node.js Some other interesting aspects of the module .

Node Modules Is it singleton mode

In the last article , We talked about Node.js Only one module is loaded at a time . If a request is made ,Node.js A cached copy of the module is given . So it looks like these modules behave like an only child . Here's an example , To illustrate this situation .
First , We created a project for the application , Initialize the application , And created a file user.js, As shown below :

1620729244339.png

next , stay APP.JS We'll use the user module in (user module), And use it as follows :

2.png

You can see that we created two users , As long as one of the variables is modified, the content of the other variable will be affected . We have to be aware that user modules are cached , And is reused in the time of another request .
Now let's change it to a constructor , See how he works

Constructors

We introduced constructors in the last article , Realized user.js Change of :

3.png

This part will continue in the following app.js Use in :

4.png

We can see two different examples , And you can intuitively feel the difference between them . Don't worry too much about different problems , Other examples and solutions will be presented later .
Now let's start with our topic , About how to use modules to manage applications .

Application building

Let's start building a simple application foundation , Next, we will continue to refine it in the process of explanation .
We've created some new folders , Now the structure included in the program is as follows :

5.png

First, we create separate folders for different modules . Now there are library management folders , The other is for the logger folder , Similar to user management . In this way, each of our modules has a focus , Easy to locate and manage . At the same time, there are subfolders in each folder . Here we need to pay attention to the folder level index.js file , It's going to be a part of the module API.
And then in app.js We can pass require Refer to the module , See the project that it works as expected . Notice how we get through require user.js To quote it .
Now let's update the code content :

6.png

We created several projects under the library management module , In this module we can see book.js Follow the common rules JavaScript Constructor Pattern ( But with user.js The constructor example you see in is slightly different ).
Corresponding index.js The following code is in the file :

7.png

index.js As a module API, Let us in app.js Use it in , As shown below :

8.png

take user.js Change to and book.js With the same constructor mode, our program is working as expected . Here's a hint , We can use Node.js Other languages in the existing JavaScript Write the content . Choose according to your preference .

Here is the code user.js What it looks like after refactoring :

9.png

summary

The application content described in this article is very basic , We learn Node.js Some basic knowledge of dependency management and some common methods of establishing project structure are used for file module management .
We also see Node.js Used in applications JavaScript Knowledge of design patterns , And also through some simple examples to illustrate .

版权声明
本文为[Grape City technical team]所创,转载请带上原文链接,感谢
https://qdmana.com/2021/06/20210602114126714K.html

  1. HTML + CSS + JavaScript to achieve cool Fireworks (cloud like particle text 3D opening)
  2. HTML + CSS + JavaScript realizes 520 advertising love tree (including music), which is necessary for programmers to express themselves
  3. Solve the problem of Web front-end deployment server (it can be deployed online without a server)
  4. HTML + CSS + JS make wedding countdown web page template (520 / Tanabata Valentine's Day / programmer advertisement)
  5. What else can driverless minibus do besides "Park connection"?
  6. Cloud native leads the era of all cloud development
  7. NRM mirror source management tool
  8. Bring it to you, flex Jiugong
  9. Lolstyle UI component development practice (II) -- button group component
  10. Deconstruction assignment in ES6
  11. Luo 2 peerless Tang clan was officially launched. The official gave a key point, and the broadcast time was implied
  12. 20初识前端HTML(1)
  13. 当新零售遇上 Serverless
  14. 20 initial knowledge of front-end HTML (1)
  15. When new retail meets serverless
  16. [golang] - go into go language lesson 5 type conversion
  17. [golang] - go into go language lesson 6 conditional expression
  18. HTML5(八)——SVG 之 path 详解
  19. HTML5 (8) -- detailed explanation of SVG path
  20. 需要开通VIP以后页面内容才能复制怎么办?控制台禁用javascript即可
  21. Web前端|CSS入门教程(超详细的CSS使用讲解,适合前端初学者)
  22. 实践积累 —— 用Vue3简单写一个单行横向滚动组件
  23. Serverless 全能选手,再下一城
  24. What if you need to open a VIP to copy the page content? Just disable JavaScript on the console
  25. Web front end | CSS introductory tutorial (super detailed CSS explanation, suitable for front-end beginners)
  26. Practice accumulation - write a single line horizontal scroll component simply with vue3
  27. Dili Reba is thin again. She looks elegant and high in a strapless hollow skirt, and her "palm waist" is beautiful to a new height
  28. Serverless all-round player, next city
  29. The difference between MySQL semi synchronous replication and lossless semi synchronous replication
  30. Vue表单设计器的终极解决方案
  31. The ultimate solution for Vue form designer
  32. Nginx从理论到实践超详细笔记
  33. Yu Shuxin's red backless swimsuit is split to the waist and tail, with a concave convex figure and excessive color matching, and his face is white to dazzling
  34. Nginx ultra detailed notes from theory to practice
  35. 【动画消消乐|CSS】086.炫酷水波浪Loading过渡动画
  36. typecho全站启用https
  37. CCTV has another popular employee. The off-site interpretation is very professional, and the appearance ability is no less than that of Wang Bingbing
  38. [animation Xiaole | CSS] 086. Cool water wave loading transition animation
  39. Enable HTTPS in Typecho
  40. 50天用JavaScript完成50个web项目,我学到了什么?
  41. 根据JavaScript中原生的XMLHttpRequest实现jQuery的Ajax
  42. What have I learned from completing 50 web projects with JavaScript in 50 days?
  43. "My neighbor doesn't grow up" has hit the whole network. There are countless horse music circles, and actor Zhou Xiaochuan has successfully made a circle
  44. 根据JavaScript中原生的XMLHttpRequest实现jQuery的Ajax
  45. Implement the Ajax of jQuery according to the native XMLHttpRequest in JavaScript
  46. Implement the Ajax of jQuery according to the native XMLHttpRequest in JavaScript
  47. 30 + women still wear less T-shirts and jeans. If they wear them like stars, they will lose weight
  48. 数栈技术分享前端篇:TS,看你哪里逃~
  49. Several stack technology sharing front end: TS, see where you escape~
  50. 舍弃Kong和Nginx,Apache APISIX 在趣链科技 BaaS 平台的落地实践
  51. Abandon the landing practice of Kong and nginx, Apache apisik on the baas platform of fun chain technology
  52. 浪迹天涯king教你用elementui做复杂的表格,去处理报表数据(合并表头,合并表体行和列)
  53. 前端HTML两万字图文大总结,快来看看你会多少!【️熬夜整理&建议收藏️】
  54. Wandering around the world king teaches you to use elementui to make complex tables and process report data (merge header, merge table body rows and columns)
  55. 路由刷新数据丢失 - vuex数据读取的问题
  56. Front end HTML 20000 word graphic summary, come and see how much you can【 Stay up late to sort out & suggestions]
  57. Route refresh data loss - vuex data reading problem
  58. Systemctl系统启动Nginx服务脚本
  59. Systemctl system startup nginx service script
  60. sleepless