SOURCE

// var total = [ 0, 1, 2, 3 ].reduce(( acc, cur ) => {
//    console.log(acc,cur)  
//     return acc + cur
// }, 0);
// console.log(total)   

// var array = [[1, 2], [3, 4], [5, 6]].reduce(( acc, cur ) => {
//    console.log(acc.concat(cur))  
//     return acc.concat(cur)
// }, []);

let names = ['tom', 'jim', 'jack', 'tom', 'jack'];

const countNames = names.reduce((allNames, name) => {
  console.log(allNames,name)
  if (name in allNames) {
    allNames[name] ++;
  }
  else {
    allNames[name] = 1;
  }
  return allNames;
}, {});

  // { tom: 2, jim: 1, jack: 2 }