TCMPP Mini Programs can operate on a variety of platforms: the iOS/iPadOS WeChat client, the Android WeChat client, the Mac WeChat client, and the WeChat Developer Tools used for debugging, among others.
In different runtime environments, the script execution environment and the environment used for component rendering are different, resulting in varying performance characteristics:
On iOS, iPadOS, and MacOS, the JavaScript code for the logic layer of the Mini Program runs in JavaScriptCore, while the view layer is rendered by WKWebView. The environments include iOS 14, iPad OS 14, Mac OS 11.4, and others.
On Android, the JavaScript code for the logic layer of the Mini Program operates within V8, while the view layer is rendered by WeChat's proprietary XWeb engine, which is based on the Mobile Chromium kernel.
On the development tools, the JavaScript code for the logic layer of the Mini Program runs within NW.js, while the view layer is rendered by Chromium Webview. JavaScriptCore cannot enable JIT compilation (Just-In-Time Compiler), resulting in noticeably lower performance under equivalent conditions compared to other platforms.
Platform differences
The differences among various runtime environments are as follows:
Inconsistencies in JavaScript syntax and API support: Developers can circumvent syntax issues by enabling the ES6 to ES5 conversion feature. Additionally, the Mini Program's basic library incorporates necessary Polyfills to compensate for API discrepancies.
Inconsistent rendering of WXSS: Despite the ability to circumvent most issues by enabling certain features, it is still recommended that developers individually inspect the actual performance of the Mini Program on each end.
The developer tools are intended solely for debugging purposes, with the final performance being determined by the client.
Operational mechanism
Mini Program Lifecycle
From initiation to eventual termination, the Mini Program undergoes various states, each exhibiting distinct characteristics.
Mini Program Initiation
From a user's perspective, the initiation of a Mini Program can be categorized into two scenarios: Cold Start and Warm Start.
Cold Start: This refers to the scenario where a user opens the Mini Program for the first time, or reopens it after it has been terminated. In this case, the Mini Program needs to be reloaded and initiated, hence termed as a Cold Start.
Warm start: This refers to the scenario where a user reopens a Mini Program within a certain time frame after having previously opened it. In this case, the Mini Program has not been terminated, but merely transitions from backend running to frontend running, a process referred to as a warm start.
From the perspective of the Mini Program's lifecycle, a cold start is generally referred to as Initiation, while a warm start is termed as Transition from Backend to Frontend.
Frontend and Backend
Upon initiation, the Mini Program's interface is displayed to the user, at which point the Mini Program runs in the Frontend.
When a user exits the Mini Program, it doesn't truly close, but rather transitions to Backend running. At this point, the Mini Program can still run for a brief period, although the usage of some APIs will be restricted. The methods of transitioning to backend running include, but are not limited to, the following:
Clicking the capsule button in the top right corner to exit the Mini Program.
Swiping rightward from the left side of the screen to exit the Mini Program on iOS system.
Pressing the "Back" button to exit the Mini Program on Android system.
While the Mini Program is running in the frontend, WeChat can be transitioned to the background directly through gestures or by pressing the Home button.
Directly locking the screen while the Mini Program is running in the backend.
When the user re-enters WeChat and opens the Mini Program, the Mini Program will once again transition to frontend running.
Terminate Mini Programs
If the Mini Program has not been used by the user for a long time, or if system resources are strained, the Mini Program will be terminated, that is, it will cease to run entirely. This includes the following scenarios:
After the Mini Program has been transitioned to the backend and suspended, if it does not re-enter the frontend for an extended period of time (currently 30 minutes), the Mini Program will be terminated.
When the Mini Program consumes excessive system resources, it may be terminated by the system or actively reclaimed by the WeChat client.
On the iOS system, when the WeChat client continuously receives system memory warnings within a certain time interval, it will proactively terminate the Mini Programs according to a specific strategy, and alert the user to insufficient running memory. Reopen the Mini Programs after that.
The specific strategy will continue to be adjusted and optimized.
Debug
Developers can debug the Mini Program using the following tools:
vConsole: vConsole allows you to view logs output by the console API and additional debugging information on your mobile device. Using it can facilitate easier identification and resolution of issues.
Source Map: Source Map can restore JS error stacks, enabling you to trace where the code has gone wrong, thereby facilitating faster code debugging.
Logs: By utilizing the built-in log function of the Mini Program, vulnerabilities can be swiftly identified and issues pinpointed. Logs record crucial operational processes and error log information. Developers can locate and resolve issues by analyzing these log details.
The aforementioned tools are essential aids when developing Mini Programs. They enable developers to debug Mini Program code more swiftly, thereby enhancing development efficiency.
Issue Summary
Usage of Webview within Mini Programs
When a Mini Program page directly loads an H5 page using webview, if there are errors in the page or if the page resources have HTTP requests as follows:
During the loading process, the following error pages may appear:
Solution
Replace HTTP resources with HTTPS resources.
QQ Share Error
Caused by: java.lang.ClassNotFoundException: Didn't find class
"org.apache.http.conn.scheme.SchemeRegistry"
If the above error occurs during QQ sharing, please add the following configuration:
Yes
No
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