SOURCE

var arr = ['8:01','9:30','11:50']
let res = 0
arr.forEach(el => {
    res += new Date('2000/01/01 ' + el).getTime()
})
const a = new Date(res / arr.length)
// console.log(`${a.getHours()}:${a.getMinutes()}`)

const sum = (n) => {
    if(n == 1 || n == 2){
        return n
    }
    return sum(n-1) + sum(n-2)
}
console.log(sum(4))