Filters

A tower uses energy, so let’s set the harvester role to bring energy to the tower along with other structures. To do this, you need to add the constant STRUCTURE_TOWER to the filter of structures your harvester is aimed at.

var roleHarvester = {

/** @param {Creep} creep **/
run: function(creep) {
    if(creep.carry.energy < creep.carryCapacity) {
        var sources = creep.room.find(FIND_SOURCES);
        if(creep.harvest(sources[0]) == ERR_NOT_IN_RANGE) {
            creep.moveTo(sources[0]);
        }
    }
    else {
        var targets = creep.room.find(FIND_STRUCTURES, {
                filter: (structure) => {
                    return (structure.structureType == STRUCTURE_EXTENSION ||
                            structure.structureType == STRUCTURE_SPAWN ||
                            structure.structureType == STRUCTURE_TOWER) && structure.energy <          structure.energyCapacity;
                }
        });
        if(targets.length > 0) {
            if(creep.transfer(targets[0], RESOURCE_ENERGY) == ERR_NOT_IN_RANGE) {
                creep.moveTo(targets[0]);
            }
        }
    }
}
};

module.exports = roleHarvester;