LUA

fivem get closest player

-- with esx
local player, distance = ESX.Game.GetClosestPlayer()

-- without esx
function GetClosestPlayer()
    local players = GetPlayers()
    local closestDistance = -1
    local closestPlayer = -1
    local ped = GetPlayerPed(-1)
    local coords = GetEntityCoords(ped)

    for i, v in ipairs(players) do
        local target = GetPlayerPed(v)
        if (target ~= ped) then
            local targetCoords = GetEntityCoords(GetPlayerPed(v))
            local distance = Vdist(targetCoords.x, targetCoords.y, targetCoords.z, coords.x, coords.y, coords.z)
            if (closestDistance == -1 or closestDistance > distance) then
                closestPlayer = v
                closestDistance = distance
            end
        end
    end
    return closestPlayer, closestDistance
end

local player, distance = GetClosestPlayer()

fivem server id of nearest player

-- with esx

local player, distance = ESX.Game.GetClosestPlayer()
if distance <= 5.0 --[[the maximum distance to the other player]] then
   local player_server_id = GetPlayerServerId(player)
end

-- without esx
function GetClosestPlayer()
    local players = GetPlayers()
    local closestDistance = -1
    local closestPlayer = -1
    local ped = GetPlayerPed(-1)
    local coords = GetEntityCoords(ped)

    for i, v in ipairs(players) do
        local target = GetPlayerPed(v)
        if (target ~= ped) then
            local targetCoords = GetEntityCoords(GetPlayerPed(v))
            local distance = Vdist(targetCoords.x, targetCoords.y, targetCoords.z, coords.x, coords.y, coords.z)
            if (closestDistance == -1 or closestDistance > distance) then
                closestPlayer = v
                closestDistance = distance
            end
        end
    end
    return closestPlayer, closestDistance
end

local player, distance = GetClosestPlayer()
if distance <= 5.0 --[[the maximum distance to the other player]] then
   local player_server_id = GetPlayerServerId(player)
end

FiveM how to check where nearest player is

For example, you could use GET_CLOSEST_PLAYER_TO_ENITY  then, check to make sure that the player is within a certain distance. There, you’ve just reduced the search from 32 players to one.

If you want to be able to cuff any ped then you could use GET_CLOSEST_PED