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

lodash's countBy function will do the trick:

_.countBy(['a', 'a', 'b', 'c', 'c']) will evaluate to: {a: 2, b: 1, c: 2}

It does involve adding lodash as a dependency though.