SOURCE

function Count(arr = []){
    return arr.reduce((t, v) => (t[v] = (t[v] || 0) + 1, t), {})
}

const arr = [0, 1, 1, 2, 2, 2];
const str = 'aabbcccc';
const arr1 = str.split('');

console.log(Count(arr));
console.log(Count(arr1));


function Position(arr = [], val){
    return arr.reduce((t, v, i) => (v === val && t.push(i), t), [])
}
console.log(Position(arr,2))