Transform data with dependencies and overrides

transformer.js

const lookUp = ({ hash, ids }) => ids.map((id) => hash[id]);

createTransformer({
  hash: getHash,
  ids: getIds,
}, lookUp, []);

const createTransformer = (dependencies, transformer, fallbackValue) => {
  return function(state, props, overrides) {
    const keys = Object.keys(dependencies);

    const dependenciesHash = keys.reduce((key) => {
      const dependency = overrides[key] || dependencies[key];
      return dependency(state, props);
    }, {});

    const output = transformer(dependenciesHash);

    if (output == null && fallbackValue != null) {
      return fallbackValue;
    }

    return output;
  };
}