In this guide, we're going to talk about comments in javascript. Every programming language I've ever worked with has a concept of comments and what comments are is they allow you to put text in your code without actually having it run. And so what will happen is you can type anything you want in these comments and then when the javascript interpreter scans through the code it recognizes what a comment is and then it completely ignores it.

Anything you put inside of it is not going to run. Before I show you the syntax for this I want to make one statement about code comments and this is something that I've seen through the years. And so I want to introduce it now. And that is that you need to be very intentional about your code comments. Because I have seen many developers especially new developers that load up their programs with all kinds of comments and what I've seen also happen is as that program develops and as they change functionality in their programs they don't always go back and update the comment.

In other words, if they say that the comment is, that a function is going to do x y z type functionality and it requires these arguments and they put that in the comment, then if they make a change and the behavior of the function changes but they don't update that then when someone else goes or even when they go back and they look at the comment later on it's going to be confusing because they're going to try to follow those instructions and they're not going to fit the updated version of the code.

So be very careful when you're typing them in. I actually rarely put comments into any code that I write and I follow the philosophy that my classes my modules my functions should be self-describing and you'll see that as we start to get into more advanced topics. I like to use very descriptive words for variables and for functions so that I don't need comments. I can actually read what I've named something and then that describes what it does. That's a little kind of a best practice when we're talking about how we organize code and how we name things that may not seem like a big deal. But the more advanced a project gets the more important naming gets. And you don't want to rely on comments because those could say anything and they can be very confusing and lead to some bugs if they're not updated.

With all that being said now let me show you actually how to use comments. There are two different ways you can do it, the first way is a single line comment. With that you just do two slashes // and then you can put anything you want after that for example.

//this line of code is commented out

As you can see the syntax highlighter shows that this is grayed out which represents that nothing is going to happen if I run this. Nothing comes out in the console literally no code gets changed whatsoever. Now that is when you have just one line of comments. Now the cool thing about this as well is you can actually put them on the same line as code as long as you put it after the code.

If I do console.log('Hi there'); // Here is another comment

You'll see this as you go through documentation and as you get further along on your javascript journey you'll see this happen quite a bit where a developer will have a single line of code and then they want to describe something that is just on that line. And so this is a good way of doing it. Now another way if you want to have multi-line comments is to use this syntax, a slash followed by an Asterix

/* and then you can
put anything you
want here on
multiple lines
*/

and then you close it off with an Asterix and other slash and then everything inside of there is going to be contained in that comment and nothing is going to happen. If you run this entire program right here you can see the only thing that gets run is the one console.log line of code. Everything else is considered a comment. That is the syntax for both types of comments that you can use in javascript.

// You can put anything you want here

console.log('Hi there'); // Here is another comment

/*
Anything
you want
here
*/

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