Helper functions for sorting arrays by multiple criteria

comparers.js

function composeComparers(...comparers) {
  return comparers.reduce((prev, curr) => (a, b) => prev(a, b) || curr(a, b));
}

function stringComparer(propLambda) {
  return (obj1, obj2) => {
    const obj1Val = propLambda(obj1) || '';
    const obj2Val = propLambda(obj2) || '';
    return obj1Val.localeCompare(obj2Val);
  };
}

function numberComparer(propLambda) {
  return (obj1, obj2) => {
    const obj1Val = propLambda(obj1);
    const obj2Val = propLambda(obj2);
    if (obj1Val > obj2Val) {
      return 1;
    }
    else if (obj1Val < obj2Val) {
      return -1;
    }
    return 0;
  };
}

function reverse(comparer) {
  return (obj1, obj2) => comparer(obj2, obj1);
}

/* - Example usage

const foodInTheHouse = [
  { what: 'cake',   daysSincePurchase: 2 },
  { what: 'apple',  daysSincePurchase: 8 },
  { what: 'orange', daysSincePurchase: 6 },
  { what: 'apple',  daysSincePurchase: 2 },
];

const foodInTheHouseSorted = foodInTheHouse.sort(composeComparers(
    stringComparer(x => x.what),
    reverse(numberComparer(x => x.daysSincePurchase))
));

console.log(foodInTheHouseSorted);
*/