Finding the positive numbers count in an ECMAScipt array

Question

All I am trying to achieve is better use of built-in ES functions.

var arr = [0, 1, 2, 3, -1, -2, -3];

function countPositiv(p, c, i, a)
{ 
  if(c > 0){
    return p+1; 
  } else {
    return p;
  }
}

var positiv = arr.reduce(countPositiv, 0);

console.log(positiv);

Answer 1

I don't think there is much to review, it looks ok. I would just do it inline, and there is no need to list arguments you are not using:

var positiv = arr.reduce(function(acc, x) {
  return x > 0 ? acc + 1 : acc;
}, 0);

Answer 2

This can easily be done using filter and length. filter creates an array comprising of values where the callback returned true. In this case, when v > 0. And since filter returns an array, we have access to length.

let positiveNumbersCount = arr.filter(v => v > 0).length;