Fibonacci

fibo.js

let i = 1 //step

//this implementation computes the sequence as an array
function fib(n) {
    if (n === 1) {
        return [1, 1]
    }
    const prev = fib(n - 1)
    const rl = prev.length
    const part = prev[rl - 1] + prev[rl - 2]
    console.log(`prev:`, prev)
    console.log(`part:`, part)
    return [...prev, part]
}

// console.log(fib(1))
// console.log(fib(5))

//this implementation computes the sum as an integer
const fibonacci = (num) => { 
    console.log(`step ${i++}`)
    console.log(`doing fib(${num})`) 
    if (num <= 1) { return num } 
    return fibonacci(num - 2) + fibonacci(num - 1) 
}

console.log(fibonacci(7))