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Hey, everyone, in the previous video, we just wrote a few JavaScript comments and we can see that

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they're working on our page.

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Actually, if you open any other age to Amelle page here, you can see that we have the alert comments

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showing this is because all of them are linked to the same JSC file.

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This is a bit annoying, but we are going to fix this in a moment before we do it.

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Let's talk a little bit about JavaScript syntax.

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So syntax regards to the rules we need to follow when writing in this language.

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So the first concept that is important to understand is about statements.

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Statements are instructions to be executed by the Web browser.

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Every statement should be finished with a semicolon in our JavaScript code is going to be composed of

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multiple statements.

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And these statements are executed in sequential order from top to bottom.

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So to test this out, let's go back to Visual Studio Code.

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Let's say he raised the alert for now.

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And I'm just going to copy this statement.

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So, as you can see, we're writing a statement which is an instruction for the browser.

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I can just write a statement.

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One.

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And right below, it's going to be statement, too.

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So we are separating them by Sammy Collins.

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So when you end a statement, you indicated we have a semicolon.

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We could write it like this.

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This is valid, but this is not recommended because your code is going to be very messy.

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So normally we use one statement, Pearline.

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So let's save this going back to our file and refreshing the page.

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We can see at the console that first the browser executed the first statement and then the second statement.

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So who's responsible for executing these statements?

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Normally, if you've learned other programming languages before, you know that we normally have to

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install them before we start using them.

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But with JavaScript, we don't need to use it because who's responsible for executing these statements?

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Is the browser.

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So every Web browser has a JavaScript interpreter.

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If you go down here, I just included a table with the interpreter for the most popular browsers.

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So Google Chrome uses V8.

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These interpreters are also called JavaScript engines.

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So inside Google Chrome, there's something called V8 that interprets our JavaScript statements and

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executes them.

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If you want more information, you can just click on these links.

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Now, moving ahead, like every other programming language, we can use comments in JavaScript.

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So if we want to write something, maybe so we can remember later.

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So going back to Visual Studio Code, if I want to explain something about this code, maybe I want

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to remember this, or maybe I just want to leave a message to another programming that is going to work

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with me.

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I can use these double forward slashes and then the browser is not going to read this.

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This is a one line comment.

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We can see that the next line is not affected.

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If we want to write multiline comments, we can just use forward slash asterisk.

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And then and it with asterisk.

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Forward slash.

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So now everything that we write inside here.

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He's going to be a comment.

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So this is a comment.

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All right.

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We can't erase this.

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So comments are also useful when we don't want to erase a line of code.

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But we wanted to be ignored for now.

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So we have this alert that was annoying us a little bit.

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So let me write it.

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And now let's say I don't want it to run every time, but I want to leave this code here because maybe

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I want to use it later.

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We could just comment the line and then the browser is going to ignore this line.

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It's actually easier to do it using a shortcut.

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So the most popular text editors have shortcuts to Torgau comments in Visual Studio Code.

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If you select one line or maybe multiple lines, you can use shift art a.

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And now we are just commenting more easily.

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And if we do it again, shift off a it's going to on comment.

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If you're having trouble, if this is not working for you, you can just go to add it and you find the

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shortcut for the toggle line comment and Targo Block comment.

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So in this case, I just want to comment out this line.

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So shift out a.

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And now this is not going to be executed.

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I can save this.

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And going back to the browser, refresh on the page, we can see that the browser is ignoring that comment.

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Now, just one last thing we need to pay attention is that Chavez script is a case sensitive language.

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So this means that we have this comment which uses the console object.

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And the name of the method we are executing here is log.

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If we try to write it like this, we have a capital C..

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This is going to return an error because JavaScript does not know any object written like this.

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The console object is reading with lowercase letters.

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So because of this, we should be very careful with the names of objects, properties and methods.

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So we don't make mistakes, that we would generate errors in our code.

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Sometimes we just create a variable and then we try to use it.

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We don't understand why our code is not working.

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And then after wasting a lot of time, we just realize that we are not writing it.

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We have the correct case.

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So have this in mind, JavaScript, this case sensitive.

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If you pay attention to this, you won't have any problem.

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So that was all for this lesson.

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Let's go like this.

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Little by little, step by step.

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And we're gonna start with a little more complex stuff in the next video.

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I'll see you then.