An introduction to the development examples of Zhihu Daily, the WeChat mini program version

This article describes the development examples of the WeChat mini program version of Zhihu Daily

I believe that everyone has been fascinated by the mini program recently, so I quickly played the mini program version of Zhihu Daily during the weekend to feel relieved. This article mainly summarizes this development experience and the pitfalls I have encountered. Friends in need can refer to it.

Let’s take a look at the renderings first

##Development environment preparation

The mini program was cracked on the second day after it came out, and WeChat downloaded the development tools on the third day. Now you only need to download the WeChat developer tools to use them,

When creating a project, select no appid, so there will be no appid verification.

Directory structure

## 1. app.js registers app logic, app.wxss global style file app.json configuration information

2. pages stores page files

3. utils tool code

4. images picture resource files

Each page in the mini program will have three files. wxml .wxss .js, corresponding to the structure, style, and logic, which is equivalent to the relationship between html css and js in the web page.

Develop the first pageThe code comes from the new project

<!--index.wxml-->
<view class="container">
 <view bindtap="bindViewTap" class="userinfo">
 <image class="userinfo-avatar" src="{{userInfo.avatarUrl}}" background-size="cover"></image>
 <text class="userinfo-nickname">{{userInfo.nickName}}</text>
 </view>
 <view class="usermotto">
 <text class="user-motto">{{motto}}</text>
 </view>
</view>

/**index.wxss**/
.userinfo {
 display: flex;
 flex-direction: column;
 align-items: center;
}

.userinfo-avatar {
 width: 128rpx;
 height: 128rpx;
 margin: 20rpx;
 border-radius: 50%;
}

.userinfo-nickname {
 color: #aaa;
}

.usermotto {
 margin-top: 200px;
}

//index.js
//获取应用实例
var app = getApp()
Page({
 data: {
 motto: 'Hello World',
 userInfo: {}
 },
 //事件处理函数
 bindViewTap: function() {
 wx.navigateTo({
  url: '../logs/logs'
 })
 },
 onLoad: function () {
 console.log('onLoad')
 var that = this
 //调用应用实例的方法获取全局数据
 app.getUserInfo(function(userInfo){
  //更新数据
  that.setData({
  userInfo:userInfo
  })
 })
 }
})

In the newly created project, you will see these codes under the index. Next, they are Introduction to wxml wxss js

##wxml

This is a description file of the page structure, mainly used for the following content

1. Use tags to specify components using

2. Use wx:for wx:if and other instructions to complete some logical processing on the template

3. Use bind* to bind events

wxss

style file, and basic css syntax The same, but the supported selector syntax is limited. See here. You can use flexbox to complete the layout.

You can also use the import command internally to introduce external style files

@import "common.wxss";

.pd {
 padding-left: 5px;
}

js

Page logic control, follow the commonJs specification

// util.js
function formatTime(date) {
 // ....
}

function formatDate(date, split) {
 // ...
}
module.exports = {
 formatTime: formatTime,
 formatDate: formatDate
}
var utils = require('../../utils/util.js')

The js here does not run in the browser environment , so codes such as window.

Use the Page method on the page to register a page

Page({
 data:{
 // text:"这是一个页面"
 },
 onLoad:function(options){
 // 页面初始化 options为页面跳转所带来的参数
 },
 onReady:function(){
 // 页面渲染完成
 },
 onShow:function(){
 // 页面显示
 },
 onHide:function(){
 // 页面隐藏
 },
 onUnload:function(){
 // 页面关闭
 }
})

When we need to change the bound data, The setData method must be called to modify before the page update is triggered, like this:

Page({
 data: {
  text: '这是一个页面'
 },
 onLoad: function() {
  this.setData({
   text: 'this is page'
  })
 }
})

Conditional rendering and list rendering

The following content comes from WeChat official documents.

The small program uses
wx:if=""

to complete conditional rendering, similar to vue's v-if

<view wx:if="{{condition}}"> True </view>

You can also use

wx:elif

and

wx:else to add an else block:

<view wx:if="{{length > 5}}"> 1 </view>
<view wx:elif="{{length > 2}}"> 2 </view>
<view wx:else> 3 </view>

wx:for

The control attribute is bound to an array, and the component can be repeatedly rendered using the data of each item in the array.

Built-in variables index (subscript for array traversal), item (each item for array traversal)

<view wx:for="{{items}}">
 {{index}}: {{item.message}}
</view>
Page({
 items: [{
 message: &#39;foo&#39;,
 },{
 message: &#39;bar&#39;
 }]
})

Use

wx:for-item

to specify the variable name of the current element of the array

Use
wx:for-index

to specify the variable name of the current subscript of the array :

<view wx:for="{{array}}" wx:for-index="idx" wx:for-item="itemName">
 {{idx}}: {{itemName.message}}
</view>

Event Binding

wxml Just use bind[eventName]="handler"

Syntax binding event

<view bindtap="bindViewTap" class="userinfo"><text>tap</text></view>
Page({
 bindViewTap: function(e) {
  console.log(e.taget)
 }
})

通过 data-* 和 e.target.dateset 传递参数

<view bindtap="bindViewTap" data-test-msg="啦啦啦啦啦啦" class="userinfo"><text>tap</text></view>
Page({
 bindViewTap: function(e) {
  // 会自动转成驼峰式命名
  console.log(e.taget.dataset.testMsg) // 啦啦啦啦啦啦
 }
})

目前踩过的坑

事件绑定中 e.target.dataset

当在父组件绑定事件和参数，点击时又子组件冒泡事件到父组件，这个时候 e.target.dataset 为空

<view bindtap="bindViewTap" data-test-msg="啦啦啦啦啦啦" class="userinfo">
 <view><text>tap</text></view>
</view>
Page({
 bindViewTap: function(e) {
  console.log(e.taget.dataset.testMsg) // undefined
 }
})

在线图片加载不稳定

在知乎日报这个项目上有大量图片需要从网上下载，这里 image 组件额显示显得极其不稳定，有很多的图片都显示不出来.

总结

微信小程序现在还在内测阶段，有很多的问题需要完善，不过对于开发速度和体验来说还是不错的，期待正式发布的那一天。以上就是本文的全部内容了，希望对大家学习使用微信小程序能有所帮助。

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