Finding lowest and highest number number value in an Array

I am struggling to workout how this code is working, how is the maxNum part working? maxNum[0] < numbers[i] how is it grabbing the last number from the array?

function sortThem(numbers) {

  let minNum = numbers[0]
  let maxNum = numbers[0]

  for (let i = 0; i < numbers.length; i++) {
    if (minNum > numbers[i]) {
      minNum = numbers[i]
    } else if (maxNum < numbers[i]) {
      maxNum = numbers[i]
    }
  }

  console.log(maxNum)

  const minMax = [minNum, maxNum]
  return minMax

}

const results = sortThem([2, 9, 10, 17, 45])

console.log(results)

>Solution :

Both start at 2 in this example

let minNum = numbers[0]//equals first element in the numbers array and thats 2 in this example
let maxNum = numbers[0]// equals 2 as well

Then you start to iterate thru the numbers array

Lets cover how you get your lowest number first:

if(minNum > numbers[i]){

1st loop
minNum = 2 not greater than 2, nothing happens
2nd loop 
minNum = 2 not greater than 9, nothing happens
3rd loop
minNum = 2 not greater than 10, nothing happens
4th loop
minNum = 2 not greater than 17, nothing happens
last loop
minNum = 2 not greater than 45, nothing happens

minNum = never changes during the entire iteration becuz no number lesser than 2 was found so it keeps the initial value

Now for the maxNum:

 } else if (maxNum < numbers[i]){

1st loop
maxNum= 2, numbers[i]=2, numbers[i] not greater than maxNum, nothing happens
2nd loop 
maxNum= 2, numbers[i]=9, numbers[i] is greater than maxNum, maxNum=9 now
3rd loop
maxNum= 9, numbers[i]=10, numbers[i] is greater than maxNum, maxNum=10 now
4th loop
maxNum= 10, numbers[i]=17, numbers[i] is greater than maxNum, maxNum=17 now
last loop
maxNum= 17, numbers[i]=45, numbers[i] is greater than maxNum, maxNum=45 now

maxNum will overwrite itself as long as you can find a number that’s higher than the value previously stored.
Hopefully that explains what you don’t understand