Creeper Spawning

var creeperList = [
    ['mule', [CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE], 1],
    ['harvester', [WORK, WORK, WORK, WORK, WORK, MOVE], 2],
    ['hauler', [CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE], 2],
    ['builder', [WORK, WORK, WORK, WORK, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, MOVE, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY, CARRY], 1],
    ['upgrader', [WORK, WORK, WORK, WORK, WORK, WORK, WORK, WORK, WORK, WORK, WORK, WORK, WORK, WORK, WORK, WORK, MOVE, MOVE, CARRY, CARRY], 1],
    ['archer', [TOUGH, TOUGH, TOUGH, TOUGH, TOUGH, RANGED_ATTACK, RANGED_ATTACK, RANGED_ATTACK, MOVE], 0],
    ['guard', [TOUGH, TOUGH, ATTACK, ATTACK, ATTACK, ATTACK, ATTACK, ATTACK, MOVE], 0],
    ['recovery', [WORK, MOVE, MOVE, CARRY, CARRY], 0],
    ];

// Creeper Spawning Code
for (var i = creeperList.length - 1; i >= 0; i--) {
    for (var p = 0, length = creeperList[i][2]; p < length; p++){
        // If there is no beta version of the creep, or if it will die before the alpha creep is born, spawn the alpha creep.
        if (Game.creeps[creeperList[i][0] + p + '_Beta'] == undefined || Game.creeps[creeperList[i][0] + p + '_Beta'].ticksToLive <= creeperList[i][1].length * 3 + 10){
            Game.spawns.Spawn1.createCreep( creeperList[i][1], creeperList[i][0] + p + '_Alpha', {role: creeperList[i][0], health: 'healthy'});
        }
        // If there is no alpha version of the creep, or if it will die before the beta creep is born, spawn the beta creep.
        if (Game.creeps[creeperList[i][0] + p + '_Alpha'] == undefined || Game.creeps[creeperList[i][0] + p + '_Alpha'].ticksToLive <= creeperList[i][1].length * 3 + 10) {
            Game.spawns.Spawn1.createCreep( creeperList[i][1], creeperList[i][0] + p +  '_Beta', {role: creeperList[i][0], health: 'healthy'});
        }

    }
}