A Javascript function returning an array with the desired length of the Fibonacci sequence

fibonacci.js

const fibonacci = length => {
    
    const fibSeq = [1, 1];
    if(length < 2) return fibSeq.splice(length, length);
    for(let i = 2; i < length; i++) fibSeq.push(fibSeq[i-2] + fibSeq[i-1]);
    return fibSeq;
    
}

console.log(fibonacci(50));