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What is Node.js
5:48In this step, we'll learn about how Node.js lets us write JavaScript programs that work without the browser.
[MUSIC]
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Hi, I'm Reggie, and
I'm an instructor at Treehouse.
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My pronouns are he, him.
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Today we'll learn about the Node.js,
JavaScript runtime environment.
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A runtime environment is
where code is executed.
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Runtime environments like Node
provide access to features of
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the JavaScript language like data types,
objects, and functions.
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Plus, they have a built in
engine that compiles code,
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translating your code into something
that computers can use and understand.
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We often run JavaScript
code in a web browser.
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Browsers like Chrome are one
example of a runtime environment.
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Browser runtimes can be
called front end runtimes.
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While the browser is one of the most
common JavaScript runtime environments,
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there are other non browser environments
Node.js being the most popular.
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Instead of using the browser, Node is used
for backend, or server-side JavaScript.
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Dynamic web applications can
be thought of as restaurants.
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While web applications have a browser
client for users to interpret and
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interact with, restaurants have a menu for
guests to understand their offerings and
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make orders.
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Servers, and I mean restaurant servers,
take the guests order,
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pass it to the kitchen,
and return with the food.
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We can think of a server in this example
as an application programming interface,
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or a way for programs to communicate.
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The kitchen in this example,
is the back end of the application.
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They take a request from a client and
return the requested resources or food.
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Backend JavaScript is often used to manage
data or interact with other applications.
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Node can be used both to make
front end applications dynamic,
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and it can be used on its own.
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Before Node developers had to use other
languages like Python to manage data,
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authenticate users, and
deliver personalized experiences.
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All JavaScript runtime environments
use the standard built in objects that
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are part of the JavaScript
programming language.
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These are called native objects, and
are often referred to as global objects.
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Different runtime environments have unique
objects that allow JavaScript code to
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execute in that specific environment.
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These are called host objects, and they're
supplied to JavaScript by the environment.
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They're only available
in that environment.
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The browser, for example, provide
the window object for accessing the DOM.
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This allows us to manipulate
the page using JavaScript.
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Node.js provides a different
set of host objects.
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For example, host objects like protocols
for requesting data, reading files,
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and others are available to JavaScript to
allow it to run outside of the browser.
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Throughout the course, you'll learn more
about some of Node's host objects and
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how to use them in your programs.
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Node is based on Google Chrome's V8
open source JavaScript engine, and
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it comes equipped with its own tools.
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The V8 engine is what compiles
JavaScript and handles memory.
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A main benefit of Node
is its non blocking,
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asynchronous execution of JavaScript code.
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In other words, it can begin executing
multiple operations at once without
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waiting for one process to complete
before moving on to the next.
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To better explain, I'll use my favorite
kind of example, one about food.
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Think of the Node environment and
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its JavaScript engine as the kitchen
of your favorite restaurant.
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A busy kitchen accepts many food orders,
often at the same time.
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The kitchen uses its resources or
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ingredients to prepare each order and
deliver it to the customer.
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A typical restaurant kitchen can
receive an order from one customer and
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start it while accepting another.
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They can begin work on one task,
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then another without being
blocked by other tasks.
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This non blocking activity makes the
process of preparing food orders faster
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and more efficient.
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Imagine if the restaurant kitchen
only accepted one order at a time and
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couldn't start another order
until the last was finished.
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Being blocked by task after task would
likely result in long wait times and
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bad reviews.
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Similar to a fast and
efficient restaurant kitchen,
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the Node runtime environment can handle
multiple tasks at the same time.
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Nodes non-blocking capabilities
allow developers to build real time,
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multi-user apps that handle many users,
events, and data requests at once.
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Because of these capabilities,
Node apps can easily scale or
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be built to serve more people.
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Netflix uses Node to stream
videos to millions of users.
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Companies like PayPal and Capital One
have increased the speed of their
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transactions when they
went from Java to Node.
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To accommodate millions of job seekers,
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LinkedIn mobile platform
is built with Node.js.
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NASA even uses Node to reduce the time
it takes to gather information from
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spacesuits.
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In this course,
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we will build two command line
applications to get familiar with Node.js.
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One to retrieve Treehouse student profile
information, and one to search for
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dictionary definitions.
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Each app will retrieve information from
the web and print it to the console.
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These apps will help you get acquainted
with some of the features of Node and
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find out why you might want
to use it in your projects.
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