Detailed explanation of the host environment for WeChat applet development

This article brings you relevant knowledge about WeChat Mini Program, which mainly introduces related issues about the host environment. WeChat mobile phone is the host environment of the mini program, and the mini program relies on the host environment The capabilities provided can realize many functions that ordinary web pages cannot complete. Let's take a look at them together. I hope it will be helpful to everyone.

[Related learning recommendations: 小program learning tutorial]

小program hosting environment

手机微信It is the host environment for mini programs. With the help of the capabilities provided by the host environment, mini programs can realize many functions that ordinary web pages cannot complete. For example: the mini program calls the API provided by WeChat to implement functions such as QR code scanning and payment.

The hosting environment of the applet contains:

Communication model

Running mechanism

Components

API

Communication model

1. The main body of communication

In the applet The main body of communication is the rendering layer and the logic layer, among which:

WXML templates and WXSS styles work in the rendering layer

JS scripts work in the logic layer

2. The communication model of the mini program

The communication model of the mini program is divided into two parts:

Rendering layer and logic layer Communication between

Communication between the logic layer and the third-party server

Both are forwarded through the WeChat client

Operating mechanism

1. The startup process of the mini program

Download the code package of the mini program to the local

Parse app.json globally Configuration file

Execute the app.js applet entry file, call App() to create the applet instance

Render the applet home page

The applet startup is completed

2. Page rendering process

Load the .json configuration file of the parsed page

Load the page .wxml template and .wxss style

Execute the .js file of the page and call Page() to create the page instance

Page rendering is completed

Component

1. Classification of components in mini programs:

The components in mini programs are also provided by the host environment. Developers can use components based on Quickly build a beautiful page structure. Officially, the components of the mini program are divided into 9 categories, which are:

• View container

• Basic content

• Form component

• Navigation component

• Body component

• map map component

• canvas canvas component

• Open capability

• Accessibility

2. Commonly used view container class components

view

Normal view area

is similar to The div in HTML is a block-level element

Commonly used to achieve page layout effects

For example: use flex to achieve horizontal layout.

wxml code:

<view class="container1">
<view>A</view>
<view>B</view>
<view>C</view>
</view>

wxss code:

.container1 view{
  width:100px;
  height:100px;
  text-align: center;
  line-height: 100px;
}
.container1 view:nth-child(1){
  background-color: aquamarine;
}
.container1 view:nth-child(2){
  background-color: azure;
}
.container1 view:nth-child(3){
  background-color: darkorange;
}
.container1 {
  display: flex;
  justify-content: space-around;
}

Achievement effect:

scroll-view

• Scrollable view area

• Commonly used to achieve scrolling list effect

Use scroll- View realizes the effect of scrolling up and down

wxml code:

<scroll-view class="container1" scroll-y>
<view>A</view>
<view>B</view>
<view>C</view>
</scroll-view>

Modified wxss code:

.container1 {
  border:1px solid red;
  height:110px;
  /*使用scroll-view时设置固定的高度*/

Achieved effect:

swiper and swiper-item

Carousel chart container component and carousel chart item component

Use these two components to achieve the carousel chart effect:

wxml code :

<swiper class="swiper-container" indicator-dots="true" indicator-color="white" indicator-active-color="red" autoplay="true" interval="1000" circular>
<swiper-item>
<view class="item">A</view>
</swiper-item>
<swiper-item>
  <view class="item">B</view>
</swiper-item>
<swiper-item>
  <view class="item">C</view>
</swiper-item>
</swiper>

wxss code:

.swiper-container{
  height:150px;
}
.item{
  height:100%;
  line-height: 150px;
  text-align: center;
}
swiper-item:nth-child(1) .item{
  background-color: aquamarine;
}
swiper-item:nth-child(2) .item{
  background-color: azure;
}
swiper-item:nth-child(3) .item{
  background-color: darkorange;
}

Achievement effect:

3. Commonly used basic content components

text

Text component

Similar to the span tag in HTML, it is an inline element

Long press to select text content The effect

<view>
长按可以选中文本内容:
<text user-select>HelloWorld!</text>
</view>

rich-text

The rich text component supports rendering HTML strings into WXML structures

Rendering HTML strings For the corresponding UI structure

<rich-text nodes="<h1 id="标题">标题</h1>"> </rich-text>

4.其他常用组件

button

按钮组件

功能比 HTML 中的 button 按钮丰富

通过 open-type 属性可以调用微信提供的各种功能（客服、转发、获取用户授权、获取用户信息等）

image

图片组件

image 组件默认宽度约 300px、高度约 240px

navigator

页面导航组件

类似于 HTML 中的 a 链接，实现页面的跳转

5.API

小程序中的 API 是由宿主环境提供的，通过这些丰富的小程序 API，开发者可以方便的调用微信提供的能力，例如：实现支付，扫码等功能。

小程序 API 的 3 大分类：

事件监听 API

• 特点：以 on 开头，用来监听某些事件的触发

• 举例：wx.onWindowResize(function callback) 监听窗口尺寸变化的事件

同步 API

• 特点1：以 Sync 结尾的 API 都是同步 API

• 特点2：同步 API 的执行结果，可以通过函数返回值直接获取，如果执行出错会抛出异常

• 举例：wx.setStorageSync('key', 'value') 向本地存储中写入内容

异步 API

• 特点：类似于 jQuery 中的 $.ajax(options) 函数，需要通过 success、fail、complete 接收调用的结果

• 举例：wx.request() 发起网络数据请求，通过 success 回调函数接收数据

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