Counting the occurrences / frequency of array elements

Question

In Javascript, I\'m trying to take an initial array of number values and count the elements inside it. Ideally, the result would be two new arrays, the first specifying each

Answer 1

I think this is the simplest way how to count occurrences with same value in array.

var a = [true, false, false, false];
a.filter(function(value){
    return value === false;
}).length