function for dynamic sorting arrays

custom-sort.js

// http://www.sitepoint.com/sort-an-array-of-objects-in-javascript
const bands = [ 
  { genre: 'Rap', band: 'Migos', albums: 2},
  { genre: 'Pop', band: 'Coldplay', albums: 4, awards: 13},
  { genre: 'Rock', band: 'Breaking Benjamins', albums: 1}
];

// function for dynamic sorting
function compareValues(key, order='asc') {
  return function(a, b) {
    if(!a.hasOwnProperty(key) || !b.hasOwnProperty(key)) {
      // property doesn't exist on either object
        return 0; 
    }

    const varA = (typeof a[key] === 'string') ? 
      a[key].toUpperCase() : a[key];
    const varB = (typeof b[key] === 'string') ? 
      b[key].toUpperCase() : b[key];

    let comparison = 0;
    if (varA > varB) {
      comparison = 1;
    } else if (varA < varB) {
      comparison = -1;
    }
    return (
      (order == 'desc') ? (comparison * -1) : comparison
    );
  };
}