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JavaScript was originally designed to run in the browser, but JavaScript can be found in other places too. JavaScript is the only web-based programming language that can run on both the front end and the back end. In this video, we'll delve into what that means.
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[MUSIC]
0:00
Hi everyone, I'm Guil,
a JavaScript teacher here at Treehouse.
0:09
JavaScript is the most popular and
0:12
versatile programming
language in the world.
0:14
And there's a lot of ground
to cover on the subject.
0:16
In this course,
you'll take a short break from coding and
0:18
continue to explore the exciting
JavaScript ecosystem.
0:22
You'll learn how Node.js help
JavaScript reach new heights.
0:25
Discover applications and
tools built with JavaScript.
0:28
And get a closer look at popular
JavaScript frameworks, libraries and more.
0:32
JavaScript was originally
designed to run in the browser.
0:36
But JavaScript can be
found in other places too.
0:39
For instance,
JavaScript is the only web-based
0:42
programming language that can run on
both the front end and the back end.
0:45
So let's delve into what this means.
0:48
Writing JavaScript that
runs on the front end or
0:51
client side means you're writing
JavaScript that runs in the browser.
0:53
Client-side JavaScript is what allows
user interactivity in web pages.
0:56
JavaScript is interpreted and executed by
the browser's JavaScript engine against
1:01
browser specific APIs, like the DOM,
or Document Object Model, for example.
1:05
The JavaScript you've written in many of
the projects so far at Treehouse, for
1:10
example, is client-side JavaScript.
1:14
You linked a JavaScript file
to an HTML file and tested and
1:16
viewed the results of
your code in the browser.
1:20
You may have selected and
1:22
manipulated elements with JavaScript too,
or used JavaScript for form validation.
1:23
So client-side JavaScript is mainly
concerned with improving and
1:28
enhancing the appearance and
behavior of the rendered web page.
1:31
Google Maps is a popular example of
an application that uses client-side
1:35
JavaScript to let you interact with a map
by moving it around, zooming in and
1:39
out, and more.
1:43
But JavaScript is not just
about working with the DOM.
1:44
Writing back end or server-side JavaScript
means that instead of writing code
1:47
that executes in the browser, you're
writing code that executes on the server.
1:51
Server-side JavaScript is used for
building APIs, databases,
1:56
web servers, and more.
2:00
Instead of dealing with the rendered page
only, server-side JavaScript can be used
2:02
to provide customized experiences for
each user's request to a website.
2:06
Writing JavaScript for
both the front end and
2:11
back end portions of an application
is known as Full-Stack Development.
2:13
How was JavaScript able to run
in different environments?
2:17
Well, host objects are supplied
to JavaScript by the environment.
2:20
That way, JavaScript code can execute
in that specific environment.
2:23
For example, the browser provides the
window object for working with the DOM.
2:27
The browser also provides document,
history, XMLHttpRequest,
2:32
and other host objects.
2:37
Now Node,
a Server-side runtime environment for
2:39
JavaScript, provides a completely
different set of host objects,
2:41
which you'll learn about
in the next video.
2:44
For now, you can read more about
host objects in the teacher's notes.
2:46
JavaScript's Native Objects are available
to you, no matter the environment.
2:50
Native Objects
are the built-in objects that
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are part of the JavaScript
programming language.
2:57
Like the string, number, array,
and math objects for example.
2:59
They're available in both the browser and
server-side environments like Node.JS.
3:03
Speaking of Node, in the next video, we'll
explore this powerful tool that can run
3:08
JavaScript applications on
the server side, client side, and
3:12
just about anywhere else.
3:15
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