On Player Leave

Introduction ​

Sourced By Bedrock Commands Community Discord

This system will run your desired commands on the event that a player leaves the world.

Note: You cannot execute commands on the players that leave using target selectors. However, you may use the On Player Join system to execute when they join back.

Setup ​

To be typed in Chat:

/scoreboard objectives add total dummy

If you are working with functions and prefer to have the objective added automatically on world initialisation, follow the process outlined in On First World Load.

System ​

## Entity Counter
### Reset current player count
scoreboard players reset NewPlayerCount total
### Get current player count 
execute as @a run scoreboard players add NewPlayerCount total 1

## Get Difference ( Current - Previous )
scoreboard players operation newPlayerCount total -= playerCount total

## Your Commands Here (Example)
### Message if there is a difference of -1 or less
execute if score newPlayerCount total matches ..-1 run say a player has left the world

## Entity Counter
### Reset current player count
scoreboard players reset playerCount total
### Get current player count (to check difference next game tick)
execute as @a run scoreboard players add playerCount total 1

Here, we have used a /say command as an example, but you can use any command you prefer and as many as you need.

Just make sure to follow the given order and properly apply the /execute if score condition as shown for your desired commands.

Explanation ​

• NewPlayerCount total number of players on the world in the current game-tick (at start of command loop).
• PlayerCount total number of players on the world in the current game-tick (by the end of command loop).

Since PlayerCount is only updated at the end of the command loop, it can be used at the start of the command loop in the next game-tick to check difference with NewPlayerCount.

The count is obtained using the Entity Counter system. It may be beneficial to refer to that page to better understand this one. When referring to that page, you will notice that we have used the objective name total instead of count. This is to prevent collision between the two systems.

By subtracting 'PlayerCount' total from 'NewPlayerCount' total, we will be able to identify if the player count has:

• decreased ..-1
• increased 1..
• or if it's unchanged 0

If it has decreased, we know that 1 or more players have left the game. Using this knowledge, we can run our desired commands from 'newPlayerCount' if it's score is -1 or less.

• i.e., if there were 10 players and someone leaves:

  • that is NewPlayerCount - PlayerCount
  • which results 9 - 10 = -1
  • hence, we will detect by ..-1

• The 'NewPlayerCount' total is obtained first, subtraction is performed after that to run your desired commands, and lastly, the 'PlayerCount' total is obtained to be used in the next game-tick.

Tick JSON ​

If you are using functions instead of command blocks, the on_leave function must be added to the tick.json in order to loop and run it continuously. Multiple files can be added to the tick.json by placing a comma after each string. Refer to Functions documentation for further info.

{
  "values": [
    "events/player/on_leave"
  ]
}

If using functions, your pack folder structure will be as follows: