For the first part I just did the following and it recognized = [] as undefined and was able to properly assign the largest value. If this fails under some condition that the longer code in the video shows, please let me know! edit* The check for an empty array with if statement appears necessary using the reduce method, but not the for loop below.
const numbers = [7,1,6,5];
const max = getMax(numbers);
console.log(max);
function getMax(array) {
let largest = array[0];
for (let num of array)
if (num > largest)
largest = num;
return largest;