How to start solving the challenge "Return Largest numbers in Array"

What are the first steps I need to do to solve this problem?

function largestOfFour(arr) {
// You can do this!

return arr;

largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);

A few ways do to this. You need a global variable to store the highest number then loop through each array.
Or use sorting.

´This one is not that hard, what happens is that usually when you look at a group of numbers, you think that you are able to pick the largest one and the smallest one just by looking at them, but in reality, you pick each one a time, and compare them to the others and “save” it in your memory until you go and find another larger one and say “ok, now this is the largest one”.

Just imagine that each of the numbers in the array is presented to you one at a time, and each time you see a new number you’re going to save it as the largest one first, and then compare it to the next number you see, if the new number is larger than your current largest one, then you’re going to change it, and so on and so forth…just let me know if this was clear enough, or maybe too clear lol