How to remove array element from an array of arrays which also has non array elements

Question

I am working on a multiplayer game and I have a room array with the following layout (I added comments for better understanding):

Room_Array
[
    [
        "Room_0",   // room name
        10,         // max people
        "Random",   // room type
        [           // now arrays of players follow
            [
               1,     // ShortID
               123,   // position X
               234,   // position Y
               10     // angle
            ],
            [
               2,
               123,
               234,
               10
            ],
            [
               3,
               123,
               234,
               10
            ],
        ]
    ]
    // here other rooms are created with the same layout as Room_0 when the max people is reached
]

How would I go around to remove the whole array of the player with ShortID = 2? in case he disconnects?

So the desired result would be:

Room_Array
[
    [
        "Room_0",   // room name
        10,         // max people
        "Random",   // room type
        [           // now arrays of players follow
            [
               1,     // ShortID
               123,   // position X
               234,   // position Y
               10     // angle
            ],
            [
               3,
               123,
               234,
               10
            ],
        ]
    ]
]

I tried the following code and in the console log it showed me the elements of the array I need to splice, so 2, 123, 234, 10. The commented splice resulted in error unidentified element 1.

for (var i = 0; i < Room_Array.length; i++)
{
    if (Room_Array[i][0] === PlayerObject[socket.id].RoomName)
    {
        for (var j = 0; j < Room_Array[i][3].length; j++)
        {
            if (Room_Array[i][3][j][0] === PlayerObject[socket.id].ShortID)
            {
                console.log("Array to splice: " + Room_Array[i][3][j]);
                //Room_Array.splice([i][3][j], 1); // error unidentified 1

            }
        }


    break;
    }
}

Is there a reason you've gone for this array structure rather than something like a json object? It would make this a lot simpler for you. — Paul Ryan
– Paul Ryan, Commented Mar 28, 2020 at 13:10
@PaulRyan I usually use json to store data, the arrays are needed as a lot of operations are done on them very fast. I'm not 100% of the performance difference and the project is very complex right now to change anything in that regard. — JeFawk
– JeFawk, Commented Mar 28, 2020 at 15:36

Guerric P · Accepted Answer · 2020-03-29 11:00:53Z

1

Here is a working solution that mutates the initial array.

const Room_Array = [
    [
        "Room_0",   // room name
        10,         // max people
        "Random",   // room type
        [           // now arrays of players follow
            [
               1,     // ShortID
               123,   // position X
               234,   // position Y
               10     // angle
            ],
            [
               2,     // ShortID
               123,   // position X
               234,   // position Y
               10     // angle
            ],
            [
               3,
               123,
               234,
               10
            ],
        ]
    ]
];
    
function removeUser (array, id) {
  array.forEach(room => {
    const [roomName, maxPeople, roomType, players] = room;
    const index = players.findIndex(([shortId]) => shortId === id);
    if(index > -1) {
      players.splice(index, 1);
    }
  });
}

removeUser(Room_Array, 2);

console.log(Room_Array);

edited Mar 29, 2020 at 11:00

answered Mar 28, 2020 at 13:13

Guerric P

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4 Comments

JeFawk Over a year ago

Thanks a lot for the help! It works great with one room, however once there are more it cuts the same index from all the subarrays. I've fixed it but I'm afraid it's a bad patch. If you'd like to see you can check this fiddle: jsfiddle.net/jefawk/f8epo0ny TLDR: added if (index > 0) { players.splice(index, 1); }

Guerric P Over a year ago

It's not a bad patch, pretty good solution as a condition for "the player was not found"

JeFawk Over a year ago

if(index > -1) is correct, i have no idea why i hated on 0

Guerric P Over a year ago

I didn't notice you wrote if (index > 0) the correct condition is if (index > -1) since 0 is a valid value for an array index

M A Salman · Accepted Answer · 2020-03-28 13:41:21Z

0

Using foreach modifying the existing array

let Room_Array=[["Room_0", 10, "Random",[[ 1,123,234,10],[2,123,234,10],[3,123,234, 10]],]];
function remove(id){
Room_Array.forEach( room => room[3].splice(room[3].findIndex( rm=>rm[0]==id),1))
};remove(2);
console.log(Room_Array);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Using map returning a new array

let Room_Array=[["Room_0", 10, "Random",[[ 1,123,234,10],[2,123,234,10],[3,123,234, 10]],]];
function remove(id){
return Room_Array.map( room => {room[3].splice(room[3].findIndex( rm=>rm[0]==id),1);return room;})
}
console.log(remove(2));

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Mar 28, 2020 at 13:41

answered Mar 28, 2020 at 13:33

M A Salman

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1 Comment

JeFawk Over a year ago

Thanks for the help! Just as Guerric P if there are more rooms the element index disappears from all the subarrays. I took his code and checked the index against -1 and then removed it, probably could have been done on what you posted too. Thanks a lot again though :) !

Paul Ryan · Accepted Answer · 2020-03-28 13:42:21Z

If you want to go down the JSON route instead, which I highly recommend, here's a working example:

const Room_Array = 
[
    {
        roomName: "Room_0",
        maxPeope: 10,
        roomType: "Random",
        players: [
            {
               shortID: 1,
               xPosition: 123,
               yPosition: 234, 
               angle: 10
            },
            {
               shortID: 2,
               xPosition: 123,
               yPosition: 234, 
               angle: 10
            },
            {
               shortID: 3,
               xPosition: 123,
               yPosition: 234, 
               angle: 10
            },
        ]
    }
];

function removeUser(id)
{
  Room_Array.forEach((room) => 
  {
    room.players = room.players.filter(player => player.shortID !== id);
  });
  console.log(Room_Array);
}

removeUser(1);

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