2

Example on how to get closest player

RegisterCommand('revive', function(source, args, rawCommand)
  local t, distance = GetClosestPlayer()
  if(distance ~= -1 and distance < 5) then
    TriggerServerEvent('ems:revive', GetPlayerServerId(t))
  end
end)

function GetClosestPlayer()
    local players = GetPlayers()
    local closestDistance = -1
    local closestPlayer = -1
    local ply = GetPlayerPed(-1)
    local plyCoords = GetEntityCoords(ply, 0)
    
    for index,value in ipairs(players) do
        local target = GetPlayerPed(value)
        if(target ~= ply) then
            local targetCoords = GetEntityCoords(GetPlayerPed(value), 0)
            local distance = Vdist(targetCoords["x"], targetCoords["y"], targetCoords["z"], plyCoords["x"], plyCoords["y"], plyCoords["z"])
            if(closestDistance == -1 or closestDistance > distance) then
                closestPlayer = value
                closestDistance = distance
            end
        end
    end
    
    return closestPlayer, closestDistance
end

function GetPlayers()
    local players = {}

    for i = 0, 31 do
        if NetworkIsPlayerActive(i) then
            table.insert(players, i)
        end
    end

    return players
end