DORDER_HELPBUILD

// function that will identify part-built structures:
var toPartiallyBuilt = function(struct) {
  return struct.status == BEING_BUILT;
}
 
// function that will find free trucks:
var busyOrders = [
  DORDER_BUILD,     // building
  DORDER_HELPBUILD, // building
  DORDER_LINEBUILD, // building
  DORDER_DEMOLISH,  // demolishing
  DORDER_REPAIR,    // repairing a building
  DORDER_RTR,       // getting repaired
  DORDER_RECYCLE,   // getting recycled (not sure about this one)
  DORDER_SCOUT      // scouting
];
var toFreeTrucks = function(droid) {
  var order = droid.order;
  return !busyOrders.some( function(busy) {return order==busy;} );
}

// get list of part-built structures:
var buildingSites = enumStruct().filter(toPartiallyBuilt);
 
// get list of free builders:
var freeBuilders = enumDroid(me,DROID_CONSTRUCT).filter(toFreeTrucks);
// Note: Should probably check that there are buildingSites before doing a costly enumDroid()
 
// get our free builders to help out where needed:
if (buildingSites.length && freeBuilders.length) {
  buildingSites.forEach(
    function(site) {
      if (freeBuilders.length) orderDroidObj(freeBuilders.shift(),DORDER_HELPBUILD,site);
    }
  )
}