# Operating Mechanism of Mini Programs

# Startup of Mini Programs

Both "cold startup" and "hot startup" are available to Mini Programs.

• Hot startup: This refers to the process of switching a Mini Program running in the background to foreground when a user wants to re-open the opened Mini Program after a certain period of time;
• Cold startup: This occurs when a user opens a Mini Program for the first time or re-opens it after its termination by Weixin.

The concept re-startup is not applicable to Mini Programs.

# Foreground/Background Status

When a user taps the Mini Program control button in the top right corner to close a Mini Program or presses the Home button on the mobile to leave Weixin, the Mini Program is not terminated but runs in the background.

When he/she re-opens Weixin or the Mini Program, the Mini Program will run from the background to the foreground.

# Termination of Mini Programs

Note: A Mini Program is terminated only after it runs in the background for a certain period of time or it occupies too much system resource.

• When a Mini Program is in the background, it will be running for 5 minutes. After that, Weixin will terminate it.
• When a Mini Program occupies too much system resource, it may be terminated by the system or Weixin app.
  • On iOS, a Mini Program is terminated when Weixin app receives the memory consumption alert for two or more times consecutively within 5 seconds, and a prompt of "This Mini Program is terminated because it slows down Weixin" will appear.
  • It is recommended that Mini Programs listen memory alert events via wx.onMemoryWarning when necessary to free up memory promptly.

Base library version higher than 1.1.0 (inclusive) and lower than 1.4.0: When the user enters the Mini Program from entries like Scan QR code, Forward etc. (with scene values of 1007, 1008, 1011 and 1025) and exits the Mini Program when it is not sticky on top, the Mini Program will be terminated.

# Re-open Logic

Start from base library version 1.4.0. Please remaining backward compatible.

Users may open a Mini Program in the following two scenarios:

A. Open homepage: Available scene values include:

B. Open a page specified by the Mini Program: the scene value can be any other value than A.

The logic of re-open a Mini Program is as follows: