resource-builder.js

function ResourceBuilder(){
    this._dependencyPromises = [];
}

ResourceBuilder.prototype._load = function () {
    // specific to the resource...
};

ResourceBuilder.prototype.addDependency = function(dep){
    this._dependencyPromises.add(dep);
}
ResourceBuilder.protototype.get = function(){
     return Promise.all([this._load()].concat(this._dependencyPromises)).then(function(){
         // both the resource and its dependencies are now loaded
         // this was done in parallel.
     });
}