Reduce object from array

obj.js

var obj = songs.reduce(function (acc, currValue) {
  var artist = currValue.artist;
  var artistCount = acc[artist] ? acc[artist] + 1 : 1;
  
  var newObj = {};
  newObj[artist] = artistCount;
  
  return Object.assign(acc, newObj);
}, {});

// ES6
const obj = songs.reduce((acc, currvalue) => {
  const artist = currValue.artist;
  const artistCount = acc[artist] ? acc[artist] + 1 : 1;
  
  return {
    ...acc,
    [artist]: artistCount,
  };
}, {});

console.log(obj); // {Mastodon: 2, Gojira: 2}