Register Mini Program

2023-03-28 12:11

App(Object)

App() is used to register the Mini Program, accepts an object as the parameter to configure the lifecycle of Mini Program. App() should be called in app.js and only be called once.

Object Parameter Description

Property	Type	Description	Trigger
onLaunch	Function	Listening to Mini Program initialization.	On completion of Mini Program initialization, invoked only once.
onShow	Function	Listening to Mini Program showing.	On startup of Mini Program or switching to foreground from background.
onHide	Function	Listening to Mini Program hiding.	On switching Mini Program from foreground to background.
onError	Function	Listening to Mini Program error.	On js error of the Mini Program.
onUnhandledRejection	Function	Listen for the unhandledrejectionevent.	Triggered when a JavaScript `Promise` that has no rejection handler is rejected.

Foreground/background definition:

When the user leaves mobile app with the close button at upper-right corner or the device Home button, the Mini Program is not directly destroyed but switched to the background.

When mobile app is started or the Mini Program is opened again, it is switched to the foreground from the background.

Only when the Mini Program stays in background for a certain time or occupies too many system resources, it is destroyed.

onLaunch/onShow Options Parameter Description

Property	Type	Description
query	Object	Current Mini Program query, parsed from the query field in the startup parameter.
path	String	Current Mini Program page address, parsed from the page field in the startup parameter, home page by default when page is ignored.
referrerInfo	Object	Source information.

This parameter can be obtained from the onLaunch method upon the first-time Mini Program startup

The parameter can also be obtained from the onShow method when the Mini Program in background is reopened with schema.

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App({
  onLaunch(options) {
    // first opening
    console.log(options.query);
	// {number:1}
  },
  onShow(options) {
    // reopening with schema from background
	console.log(options.query);
	// {number:1}
  },
})

referrerInfo attribute description

Property	Type	Description	Compatibility
appId	string	Source Mini Program.
sourceServiceId	String	Source plug-in, visible in the plug-in running mode.	1.11.0
extraData	Object	Data transferred from the source Mini Program.

Notes:

Do not operate page stack like redirectTo/navigateTo on the onShow.

The basic library version used in AppContainer currently is 1.14.2.

onHide()

The onHide() method will be triggered when Mini Program changes to background from foreground.

Sample code

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App({
  onHide() {
    // when changes to background
    console.log('app hide');
  },
});

onError()

The onError() method will be triggered when script error happens.

Sample code

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App({
  onError(error) {
    // the Mini Program script error happens
    console.log(error);
  },
});

onUnhandledRejection()

The onUnhandledRejection() method will be triggered when a JavaScript Promise that has no rejection handler is rejected.

Sample code

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App({
  onUnhandledRejection(res) {
    // A JavaScript Promise that has no rejection handler is rejected.
    console.log(res.reason, res.promise);
    //res.reason describes the rejection reason and res.promise describes the rejected Promise.
  },
});

Global Data

Global data can be configured in App(). Other pages can get and modify the global data directly.

Sample code

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// app.js
App({
  globalData: 1
});

FAQ

Q: Can Mini Program be closed in app.js?

A: No, Mini Program can only be closed by clicking close button in the top right corner.