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All right.
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Welcome back guys.
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In the last lesson we saw how we could use the alert keyword in javascript to create a pop up in our
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browser and the pop up would say whatever is in between the two round brackets. In this case it would
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be Hello.
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Now how does the browser know which part of this code is actual code i.e. keywords like alert and which
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parts of this line is the text that we want to display?
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Well there’s something that we've added here that tells the browser that this is a string, and the secret
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is of course these two little quotation marks because everything that they enclose gets interpreted
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by the computer as a string so that it gets taken out of the code and gets interpreted as text.
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And this is really important because all the code that we write is written with text, right, with characters
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in the English alphabet.
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And it's really important that the computer knows which parts are the code and which parts are the text.
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And this is a great place to introduce you to something called data types because a string is exactly
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that.
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It's a data type.
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It's a way of classifying data to tell the computer how the program intends to use the data.
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In this case it's simply the text that we want to be displayed in our pop up and you will see this data
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type across all programming languages and it's pretty much always called a string.
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And that's because it's simply a string of characters just as you would have a string of pearls.
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And in the coming lessons whenever I refer to string I'm always talking about text that's not meant
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to be interpreted as code or just a string of characters.
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Now there are other data types other than strings.
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For example there are numbers, and numbers, because they have different symbols from the alphabet than
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we use for code,
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then we don't actually need any special symbols to tell the computer that this is a number.
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We can just simply type the number. And finally, the last data type I want to show you is the boolean.
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And this is the data type that describes data that is either true or false.
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And we're going to be using a combination of all of these data types in order to create the programs
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and the web sites in the coming lessons and modules.
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So this really is the groundwork and it's the fundamentals of how all programming languages work.
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So let's take a look at this in more detail.
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I want you to open up your console so you can do that by going to View, Developer, Javascript Console,
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and you'll see it show up down here. And, in the console,
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you can do a number of things. So you can, for example, add numbers to each other.
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So 2 + 3 equals 5.
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And you get an output after you hit enter. You can also write the code that we wrote before which is the
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alert keyword and that tells the browser that we want a pop up that says the output of 2 + 3.
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So once I hit enter I will get a pop up that says 5.
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Now I want to show you another keyword other than the alert,
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and this is called typeof.
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And this actually tells you what is the data type of whatever it is that you put within these round
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brackets.
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So, for example, if I put 23 in here, then I will get the output of,
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this is a number, but if I wrote something like typeof my name inside some quotation marks, then I
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get told that this is a string.
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And finally, let's just, for completion sake, use a boolean, for example true, then I get told that this
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is a boolean.
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So in the coming lessons and modules we'll be using all of these different data types in order to create
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our web sites and web apps. And understanding the fact that different pieces of data can have different
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data types will be a foundation block towards building those web sites and web apps.
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Now, in the next lesson we're going to talk about another foundation block for all programming languages,
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which is the variable.
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So for all of that and more, I’ll see you on the next lesson.