I don't understand any of this...

I've also been staring at this particular video for at least an hour trying to wrap my brain around it; in a lot of ways it builds off of a lot of the stuff already covered in the "JavaScript Basics" course that I was having trouble recalling on account of so much information flying at me so quickly.

Basically the way I see it is, after having taken dozens of pages of notes, IMHO pretty much every single term, keyword, concept, and so on needs some kind of quotation marks or a parentheses or an asterisk or SOMETHING that helps further explain it. Here's what I came up with for this section in particular.

You'll note the heavy use of quotation marks and exclamation points...this is entirely me yelling at myself so I apologize if it seems aggressive. : D

var playList = [
  'I Did It My Way',
  'Respect',
  'Imagine',
  'Born to Run',
  'Louie Louie',
  'Maybellene'
];

Here is where confusion can start to occur!

function print(message) {
  document.write(message);
}

The word "message" used in the () for the "print" function seen above is simply a parameter, which means it's not necessarily used for anything besides being a "placeholder" word that gets replaced with any information "sent to" the "print" function each subsequent time it's called!

In this example, it's the "listHTML" variable that's nested inside the "printList" function (which can be seen in the third part of example code)!

...Doesn't take long to get to the point where even MORE confusion can occur!

function printList( list ) {
  var listHTML = '<ol>';
  for ( var i = 0; i < list.length; i += 1 ) {
    listHTML += '<li>' + list[i] + '</li>';
  }
  listHTML += '</ol>';
  print(listHTML);
}
printList(playList);

The word "list" used in the () for the "printList" function seen above is simply a parameter, which means it's not necessarily used for anything besides being a "placeholder" word that gets replaced with any information "sent to" the "printList" function each subsequent time it's called! In this example, it's the "playList" array that was declared at the very beginning of this JS code!

Since the array is in the parantheses directly following the called "printList" function on the last line, the information in the "playList" array is "sent to" to "printList" function, which then follows the "for" loop that builds the ordered HTML list that appears on the page!

Hope this helps! (If anyone wants to jump in & let me know I'm completely wrong here, please let me know.)

I assume the "list" you are talking about is the parameter of the "printList" function that is defined starting on line 14 of "playlist.js". A parameter name is just a placeholder for the argument that will be passed in when the function is actually called. On line 22 it is called with the argument "playList", and "playList" is defined starting on line 1.

At about 5:06 in the video, you can see where "print()" is defined starting on line 10 of "playlist.js".

The "index.html" file does not contain the list. As I mentioned already, the list is the first thing in "playlist.js". The "printList" function combines the list with some HTML tags to make it look nice, and then adds it to the page.

Thanks Seth for the very thorough response. I was confused by the placeholder as well...crystal clear now.

Can someone explain the relationship between the print & printList functions? It seems that the print function is called inside of the printList function. If we were to do them separately, what would print output & what would printList output?

Thank you