# Registration Weixin Mini Program

Each Weixin Mini Program needs to be in theapagejscallsAppmethods to register instances of Mini Programs, bind lifecycle callback functions, error listening, and page non-existent listening functions.

Please refer to App reference document for detailed parameter meaning and usage.

// app.js
App({
  onLaunch (options) {
    // Do something initial when launch.
  },
  onShow (options) {
    // Do something when show.
  },
  onHide () {
    // Do something when hide.
  },
  onError (msg) {
    console.log(msg)
  },
  globalData: 'I am global data'
})

The entire Weixin Mini Program has only one app instance, which is shared by all pages.Developers can obtain a globally unique App instance bygetAppmethod, obtain data on the App, or call functions that the developer registers onApp.

// xxx.js
const appInstance = getApp()
console.log(appInstance.globalData) // I am global data