Using Array methods

Ok Hi guys. So I just completed the using arrays method lesson. Now Dave McFarland went through it step by step explaining why he made each decision and I could follow along perfectly. The problem for me however is understanding, why he in the order he did and could it be done with the same exact code but in a different order. You see if I was given the task to create a search engine for a site I could have probably come up with something but I probably wouldn't have considered all the things he did and in that order.

So he used a while loop, made it true so it was a wild loop. His next step was to create a search prompt that would loop continuously. Next he create an if statement to check to see if the user typed the word 'exit' which out break out of the infinite loop, then an else if in case the user typed something else like 'list' which would use the .join method to list all the products in stock and print it to the page, then finally he use an else statement to test to see if the user searched for a specific item in the store. Inside the else statement he created another if statement with two branches, one if the product was in the array and another if it was not.

1. Why and how did he know to put the program to first exit or list before the program to search the array?
2. Could he have put the program to search the array first then the program to list or exit the search after?
3. When creating programs that have to execute many functions, how do we decide what comes first and what goes last?

I tried rewriting the program to put the search for the array last. It worked to some extent. When I typed exit, it did exit the program but at the same time printed, exit is not in stock the list works well and the searching the array also works well. here's a look at the code Dave wrote

var inStock = [
'apples',
'eggs',
'milk',
'cookies',
'cheese',
'bread',
'lettuce',
'carrot',
'broccoli',
'pizza',
'potato',
'crackers',
'onion',
'tofu',
'frozen dinner',
'cucumber'
];
var search;

function print(message) {
  document.write( '<p>' + message + '</p>');
}

while (true) {
  search = prompt('Search for a product in out store. Type "list" to show all the products in our store and "quit" to exit.')
  search = search.toLowerCase();
  if (search === 'exit') {
    break;
  } else if (search === 'list') {
    print(inStock.join(', '));
  } else {
    if (inStock.indexOf(search)> -1) {
      print('Yes. We have ' + search + ' in stock.')
    } else {
      print(search + ' is not in stock.')
    }
  }
}

Here's the way I rewrote it.

var inStock = [
'apples',
'eggs',
'milk',
'cookies',
'cheese',
'bread',
'lettuce',
'carrot',
'broccoli',
'pizza',
'potato',
'crackers',
'onion',
'tofu',
'frozen dinner',
'cucumber'
];
var search;

function print(message) {
  document.write( '<p>' + message + '</p>');
}
while (true) {
  search = prompt('Search for a product in out store. Type "list" to show all the products in our store and "quit" to exit.')
  search = search.toLowerCase();
  if (inStock.indexOf(search) > -1) {
    print('Yes. We have ' + search + ' in stock.')
  } else {
    print(search + ' is not in stock.')
  }
  if (search === 'exit') {
    break;
  } else if (search === 'list'){
    print(inStock.join(', '));
  }
}

This is a long question, so thanks in advance. I want to know how to approach writing program, how to adjust my thinking.