编辑代码

function feibo(n) {
    if (n < 1) {
        return 0
    }
    if (n === 1 || n === 2) {
        return 1
    }

    let prePre = 0
    let pre = 1

    for (let i = 1; i < n; i++) {
        let current = prePre + pre
        prePre = pre
        pre = current
    }
    return pre
}

function feibo(n) {
    if (n < 1) {
        return 0
    }
    if (n === 1 || n === 2) {
        return 1
    }
    return feibo(n - 1) + feibo(n - 2)
}

console.log(feibo(0))
console.log(feibo(1))
console.log(feibo(2))
console.log(feibo(3))
console.log(feibo(4))
console.log(feibo(5))