Wechat applet new version prompt update

Wechat applet new version prompt update

The company's small program project goes online , There will be small version iterations later . In order to enable users to use the functions of the latest version in time after our version iteration . Do the following optimization …
Knowledge point 1: When the user clicks the upper left corner to close , Or press the device Home Key to leave wechat , The applet was not destroyed directly , It's backstage ;
When you enter wechat again or open the applet again , It will enter the front desk from the backstage , Only when the applet enters the background for a certain time , Or the system resources are too high , Will be really destroyed .

Knowledge point 2: The startup of small programs is divided into " Cold start " and “ Hot start ”.
Hot start means : After the applet opens , Over a period of time （ at present ：5 minute ） Opened again , The applet in the background will be switched to the foreground .
Cold start means : After the applet is first opened or destroyed, it is opened again

Knowledge point 3: An updated version
Cold start , If a new version is found , The new version of the code package will be downloaded asynchronously , At the same time, it starts with the local package of the client , That is, the new version of the applet will not be applied until the next cold start .
If you want to apply the latest version right away , Use wx.getUpdateManager API To deal with .
The code is as follows :

//  stay app.js Write the following code in 
  onLaunch () {
    if (wx.canIUse('getUpdateManager')) {
      const updateManager = wx.getUpdateManager()
      updateManager.onCheckForUpdate(function (res) {
        console.log('onCheckForUpdate====', res)
        //  Call back after requesting new version information 
        if (res.hasUpdate) {
          console.log('res.hasUpdate====')
          updateManager.onUpdateReady(function () {
            wx.showModal({
              title: ' Update hints ',
              content: ' The new version is ready , Restart application or not ？',
              success: function (res) {
                console.log('success====', res)
                // res: {errMsg: "showModal: ok", cancel: false, confirm: true}
                if (res.confirm) {
                  //  The new version has been downloaded , call  applyUpdate  Apply new version and restart 
                  updateManager.applyUpdate()
                }
              }
            })
          })
          updateManager.onUpdateFailed(function () {
            //  New version download failed 
            wx.showModal({
              title: ' There is a new version ~',
              content: ' The new version is online ~, Please delete the current applet , Search again open ~'
            })
          })
        }
      })
    }
  }

Knowledge point 4: When the applet is reinitialized, it will trigger onLaunch event . onLaunch The event will be triggered on the page onShow Before the incident . The updated version of the applet can be written in onLaunch in .

Knowledge point 5:
The version update cannot be tested in the development and experience version
It needs to be in the developer tool , Select... At compile time " Simulation update compilation "

![ Insert picture description here (https://imgconvert.csdnimg.cn/aHR0cHM6Ly91cGxvYWQtaW1hZ2VzLmppYW5zaHUuaW8vdXBsb2FkX2ltYWdlcy8yMzEzMDY1LTc5NWU3MzJhN2VjMWI5NDkucG5n?x-oss-process=image/format,png)
( Some developer tool versions , Every time update This option needs to be checked again during compilation )
Click ok , recompile .
The page will pop up :

Click ok ：

Console display ：

Knowledge point 6: With the continuous updating of small programs , Some functions may require the latest version of wechat client to use . At this time, you can pop up a window to prompt the user to update to the latest version of wechat

if (wx.canIUse('getUpdateManager')) {
  ...
} else {
  // can't use getUpdateManager
  wx.showModal({
        title: ' Tips ',
        content: ' Current wechat version is too low , This feature is not available , Please upgrade to the latest wechat version and try again .'
   })

Full version ：

onLaunch () {
    if (wx.canIUse('getUpdateManager')) {
      const updateManager = wx.getUpdateManager()
      updateManager.onCheckForUpdate(function (res) {
        if (res.hasUpdate) {
          updateManager.onUpdateReady(function () {
            wx.showModal({
              title: ' Update hints ',
              content: ' The new version is ready , Restart application or not ？',
              success: function (res) {
                if (res.confirm) {
                  updateManager.applyUpdate()
                }
              }
            })
          })
          updateManager.onUpdateFailed(function () {
            wx.showModal({
              title: ' There is a new version ~',
              content: ' The new version is online ~, Please delete the current applet , Search again open ~'
            })
          })
        }
      })
    } else {
      wx.showModal({
        title: ' Tips ',
        content: ' Current wechat version is too low , This feature is not available , Please upgrade to the latest wechat version and try again .'
      })
    }
  }

Knowledge point 7: If in onLaunch In order to make a request , This is an asynchronous request . If there are requirements for interaction sequence , Such as : Version update – Retrieve data -- User presentation , Then it needs to be considered in callback To retrieve the data in .

Knowledge point 8:
When the applet starts , Normally, it will be hot updated , Download the new version of the package , The next boot will use the new package . However, it is found that the update is unsuccessful .
The official answer is : The effectiveness of the policy is related to the network environment, release time and other factors , Will let the applet update as quickly as possible , But there is no guarantee that every hot update will succeed .

Knowledge point 9:
Asynchronous updates of applets occur during cold start . Hot updates are not officially recommended . reason :

Official documents – to update

Reprinted from ： Simple books
The original author ： Little devil Fairy
link ：https://www.jianshu.com/p/4f5e3faaf483