An example of a composer higher order function for my How to Grok a Higher Order Class article

chof.js

// Our higher order function which logs all returned values to the function properties on an object
function attachLogger(objectOrFunction) {
  if(typeof objectOrFunction === 'function'){
    return function() {
      let ret = objectOrFunction.apply(this, arguments);
      console.log(ret);
      return ret;
    }
  }
  
  for (name in objectOrFunction){
      let method = objectOrFunction[name];
      if (typeof method === "function"){
          objectOrFunction[name] = attachLogger(objectOrFunction[name]);
      }
  }
  return objectOrFunction;
}

// we have component which fetches a price in pennies
const PriceFetcher = {
  getPriceInPence : function(productId) {
    // .. fetch price from API
  }
};
const performSomeAction = function() {
  // ...
};

// attach logging functionality
PriceFetcher = attachLogger(PriceFetcher);
performSomeAction = attachLogger(performSomeAction);