Javascript count duplicates and uniques and add to array

Question

I\'m trying to count duplicates in an array of dates and add them to a new array.

But i\'m only getting the duplicates and the amount of times they exist in the array. <

Answer 1

For that, you can use .reduce:

var arr = ['a','a', 'b', 'c', 'c'];
var result = arr.reduce(function(p,c){
  if(p[c] === undefined)
    p[c] = 0;
  p[c]++;
  return p;
},{});

console.log(result);