Detailed explanation of the usage of App() function in WeChat mini program

This article brings you a detailed explanation of the usage of the App() function in the WeChat applet. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

The App() function is used to register a small program and accepts an object parameter, which specifies the life cycle function of the small program, etc.

Object parameter description

1.onLauch

Life cycle function, monitors the initialization of the applet, and will be triggered once when the initialization of the applet is completed.

Do not call getCurrentPages() during onLauch, the page has not yet been generated.

2.onShow

When the applet starts, or enters the foreground from the back, onShow will be triggered

3.onHide

When the applet enters from the front In the background, onHide

4.onError

will be triggered when a script error occurs in the applet or the api call fails, onError will be triggered with error information.

5.onPageNotFound

When the applet fails to open the page, it will call back this function with the page information.

(1) If the developer does not add an onPageNotFound listener, when the jump page does not exist, a non-existence prompt page for the native WeChat client page will be pushed.

(2) If the onPageNotFound callback is redirected to another page that does not exist, a prompt page that the WeChat client's native page does not exist will be pushed, and the callback onPageNotFound will not exist

6. Other

developers can add any functions or data to the Object parameter, which can be accessed using this.

Definition of frontend and backend:

When the user clicks on the upper left corner to close, or presses the device's Home button to leave WeChat, the mini program is not directly destroyed, but enters the background. When you enter WeChat again or open Xiaocheng again, you will enter the foreground from the background.

The global getApp() function can be used to obtain mini program implementation examples.

// other.js
var appInstance = getApp()
console.log(appInstance.globalData) // I am global data

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