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In order for JavaScript to do anything, it must be given information to work with. We call that information data. JavaScript supports a number of different data types. This video covers common data types like numbers and strings.
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All right, let's write some JavaScript.
0:00
Now I'll teach you the parts you need
to know to get started with JavaScript
0:02
development like, common data types,
variables, arrays, objects, loops,
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functions, and more.
0:09
The most common place you'll
encounter JavaScript and
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the easiest place to try out JavaScript
programming is in a web browser.
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In fact, JavaScript got its start
in the browser back in 1995.
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Browsers have a built-in JavaScript
interpreter that reads, understands, and
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runs the instruction in
a JavaScript program.
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To get started now,
all you need is your browser and
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the console built-in to
the browser's developer tools.
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I'm using Google Chrome.
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So once you have a tab open in Chrome, you
can find the developer tools in the top
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right menu by going to More Tools
then clicking Developer Tools.
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You may have you used dev tools before to
inspect the HTML and CSS of a web page.
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So here in the console tab you
can write and run JavaScript.
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Now don't worry about every bit of
JavaScript code you'll see in this video.
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You don't have to understand everything or
most of what I'll cover.
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If you pick up just enough
to get started learning and
1:00
writing JavaScript, that's great.
1:02
In order for JavaScript to do anything,
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it must be given information to work with,
we call that information data.
1:05
JavaScript supports a number
of different data types.
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Now, I'm not gonna cover all of them here,
but
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I will cover common data types
like numbers and strings.
1:15
For example,
a number like 20 is a numeric data type.
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And numbers in JavaScript are used for
making calculations like adding,
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subtracting, computing total costs, even
keeping track of a game score and more.
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And numbers can be whole numbers or
numbers with decimal points, so for
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instance if I type 20 + 50.5 into
the console, and press the Enter key.
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The console runs this code and
prints the total, 70.5.
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And JavaScript provides arithmetic
operators like the plus sign that perform
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all common mathematical calculations like
addition, subtraction, multiplication, and
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division.
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So, go ahead and
try a few other calculations on your own.
1:56
One of the easiest ways to clear
the console is by control or
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right-clicking in the console and
selecting Clear console or
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clicking the Clear console icon
just above the console output.
2:07
Another common data type
in JavaScript is a string.
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Strings are used for words, sentences,
and other text in your program.
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And you write a string as
a series of letters, numbers, and
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other characters inside single or
double quotation marks.
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So for example, in between quotes,
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I'll type the message hi, my name is Guil.
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Now I'll write a simple command
that uses this string to
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display a dialogue box to users.
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I'll use the JavaScript alert function for
this.
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Alert is a browser specific function or
command used to pop up and
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alert dialogue in the browser.
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So between the parenthesis you'll
provide alert the message to display.
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I'll pass it the string,
hi, my name is Guil.
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I'll add a semi-colon to the end.
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And when you run this code
by pressing the Enter key,
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it opens a dialog box in the browser and
displays a message, hi my name is Guil.
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So what I've written here
is a JavaScript statement.
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And throughout this video,
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you'll notice that all JavaScript
statements end in a semi-colon.
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While alert only displays a message
in a dialog box, browsers
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also provide a simple command that
captures input from site visitors, prompt.
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Prompt lets you ask a question and
get a response from the user.
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And like alert, you provide
a message between the parenthesis.
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So I'll pass prompt the string,
what is your name?
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When I run this code,
the browser prompts me to input some text
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before I can interact with
the rest of the page.
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So in the dialog box,
I see the message, what is your name?
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I'll type Guil and
click OK or press Enter.
4:00
And notice how my response
shows up in the console.
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The browser captures the response and
returns the value, the string Guil.
4:09
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