Express project creation and its routing introduction

Catalog

Express Introduce

Use Express Create project

Express Project creation

Express Project structure analysis  

Express route

Express Introduce

Express It's the smallest , agile Node.js Web Application framework , It provides a powerful set of functions to develop Web And mobile applications . It helps to be based on Node Web Rapid development of applications .

Express Framework of the Core functions yes ：

• Allow to set up middleware response HTTP request
• Defines a method for executing based on HTTP Methods and URL Routing table of different actions
• Allow dynamic rendering based on parameters passed to the template HTML page

install Express 

install Express The framework is used globally npm, So that it can be used node Terminal creation Web Applications .

npm install -g express 

Use Express Create project

Express Project creation

Use cmd Command window

1、 Enter working directory （ Customize ）

2、 Execute the create command , Create a file called hello Of Express project   --->express hello

  Indicates the successful installation interface

3、 Get into hello Directory installation dependent packages ：

   F:\hello> npm  install

4、 After installation , Execute the command to start the application ：

   F:\hello>npm  start

5、 Enter... In the browser http://localhost:3000/

In the use of WebStorm When creating a project, directly select the project option as express You can directly create .

Express Project structure analysis  

• bin： Startup profile , stay www Modify the operation port number in
• node_modules： Store all project dependency Libraries , It's like java Storage rack bag
• public： Used to hold static resource files picture ,CSS,JAVASCRIPT file ..
• routers： The routing file is equivalent to springmvc Medium Controller,ssh Medium action
• views： Where the pages are stored
• package.json： Projects depend on configuration and Developer Information .
• app.js： Apply core profile , Project entrance

Express route

Routing is used to determine how the application responds to client requests to specific endpoints , Contains a URI（ Or the path ） And a specific HTTP Request method （GET、POST etc. ）.

Each route can have one or more handler functions , These functions are performed during route matching . It is used in the following form ：app.method(path,handler)

app ： yes express Example ;

method： yes HTTP Request method

path： It's the path on the server

handler： It is a function executed during route matching

If There are multiple routing handlers , If it is not the last route , Its parameters should have next：

next() The function is not Node.js or Express API Part of , It is the third argument passed to the middleware function .next Function is mainly responsible for handing over control to the next middleware , If the current middleware does not terminate the request , also next Not called , Then the request will be suspended , The middleware defined later will not get the opportunity to be executed .