Introduce Partial Application

part-app.js

const priceByCommodityAndCountry = {
  'MANGO': [
    {
      origin: 'US',
      price: 101
    },
    {
      origin: 'BR',
      price: 120
    }
  ],
  'BANANA': [    
    {
      origin: 'US',
      price: 111
    },
    {
      origin: 'MX',
      price: 90
    }
  ],
  'APPLE': [
    {
      origin: 'US',
      price: 67
    },
    {
      origin: 'BR',
      price: 66
    }
  ]
};

const EXPENSIVE_THRESHOLD=100;

function getExpensiveFruitSoldByCountry(targetCountry){
  let expensiveFruit = [];

  function isFromCountry(sourcedFruit){
    return hasOrigin(sourcedFruit,targetCountry);
  }

  function isExpensive(sourcedFruit){
    return isMoreExpensiveThanThreshold(sourcedFruit,EXPENSIVE_THRESHOLD);
  }

  Object.entries(priceByCommodityAndCountry).forEach( function([fruitName,sourcedFruits]){
    sourcedFruits.forEach( function(sourcedFruit){
      if( !isFromCountry(sourcedFruit) ){
        return;
      }
      if( !isExpensive(sourcedFruit) ){
        return;
      }
      expensiveFruit.push(fruitName);
    });
  });

  return expensiveFruit;
}

function hasOrigin(fruit,origin){
  return fruit.origin === origin;
}

function isMoreExpensiveThanThreshold(fruit,threshold){
  return fruit.price > threshold;
}


console.log('expensive fruit:');
console.log('US:', getExpensiveFruitSoldByCountry('US'));
console.log('MX:', getExpensiveFruitSoldByCountry('MX'));
console.log('BR:', getExpensiveFruitSoldByCountry('BR'));