[wechat applet] the hosting environment of the applet

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Series column ： Basic course of applet development
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Host environment

One 、 What is the host environment ？

Host environment ( host environment) It refers to the dependent environment necessary for the program to run .
for example ：Android Systems and iOS The system is two different host environments . Android version of wechat App No iOS Operating in the environment , therefore ,Android It is the host environment of Android Software , Software that leaves the host environment is meaningless ！

Two 、 The host environment of the applet

On mobile phone , The hosting environment of the applet is our mobile wechat , Typically, applets can be implemented by leveraging the capabilities provided by the hosting environment , It can complete many functions that ordinary web pages can't ： Wechat payment , Wechat code scanning , Wechat login, positioning, etc .

3、 ... and 、 What the applet hosting environment contains

1. Communication model

The subject of communication

The main body of communication in applet is rendering layer and logic layer , among :

1. WXML Templates and WXSS Styles work in the render layer
2. JS Scripts work at the logical level
   

Communication model of applet

The communication model in the applet is divided into two parts ( Are forwarded by wechat clients )

• Communication between rendering layer and logic layer
  

• Communication between logical layer and third-party server
  

2. Operating mechanism

The process of starting an applet

1. Download the code package of the applet to the local
2. analysis app.json Global profile
3. perform app.js Applet entry file , call App() Create an instance of the applet
4. Rendering applet home page
5. Applet startup completed

Applet page rendering pass

1. Load the of the parsing page .json The configuration file
2. To load a page .wxml Templates and .wxss style
3. Execute the .js file , call Page() Create page instances
4. Page rendering complete

3. Components

Components in the hosting environment are also provided by , Developers can quickly build a beautiful page structure based on components . Officials divide the components of small programs into 9 Categories: , Namely :

1. View container
2. Basic content
3. Form components
4. Navigation components
5. Media components
6. map Map components
7. canvas Canvas components
8. Opening ability
9. Accessibility

4.API

Small program official API It is divided into the following 3 Categories: :

1. Event monitoring API
   characteristic : With on start , Used to monitor the trigger of some events
   give an example : wx.onWindowResize(function callback) Listen for window size changes

2. Sync API
   characteristic 1: With Sync At the end of the API It's all synchronous API
   characteristic 2: Sync API The results of the implementation of , You can get directly through the return value of the function , An exception will be thrown if there is an error in execution :wx.setStorageSync("'key" , 'value') Write content to local storage

3. asynchronous API
   characteristic : Be similar to jQuery Medium $.ajax(options) function , Need to pass through success、fail、complete Example of result of receive call :wx.request() Initiate a network data request , adopt success The callback function receives data

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