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Welcome back in this lesson I'm going to introduce Express which is the framework that we're going to

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use throughout the rest of this course.

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There are three main questions that I want to answer here.

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The first one is what is a framework.

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How is it different from a library.

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The next is what is express.

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And then the last one is Why are we using EXPRESS Why are we teaching express in particular.

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Let's get going and we'll start by talking about what a framework is.

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Up until this point we've used a few libraries including Jay equerry and bootstrap but also some people

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would refer to the Cat me and knock knock jokes packages as libraries are definitions so far of a library

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is that it's code that someone else wrote that we can include in our application and use.

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So that's also what frameworks our frameworks are code that someone else wrote.

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Usually a lot of people wrote because it's a lot more code that we can use instead of our application

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.

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But the way that we use them is very different.

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So I have a great stack overflow post I'm going to pull up and it talks about the difference between

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a framework and a library.

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And this first answer really nails it on the head so I'll just read a few of the more important lines

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including this first one.

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The most important difference and in fact the defining difference between a library and a framework

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is something called inversion of control.

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What does this mean.

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Well it means that when you call a library you're in control but with a framework that control is inverted

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.

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The framework calls you and then I'll skip down to this section here.

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Basically all the control flow is already in the framework and there's just a bunch of predefined white

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spots that you can fill out with your own code a library on the other hand is a collection of functionality

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that you can call those two excerpts do a great job of summarizing the differences both frameworks and

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libraries are external code that you're including in your own application but a library is something

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that you're in control of if you want to use a library you can use one method 10 methods just like if

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we include a query.

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It's up to us which parts of it we use.

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We might only use a few of the methods for animations or we might use 100 different methods with a framework

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on the other hand.

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We give up a little bit of control where if we use a framework like the one we're going to use which

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is express We have some decisions that have been made for us that we have to abide by in order to use

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the framework I like to think of it a little bit like Mad Libs where a framework gives us the basic

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scaffolding and then we fill in the blanks with the important parts.

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But I want to make it really clear the point of a framework is not to replace any sort of creativity

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or homogenize the way that all applications work.

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What frameworks really do is they take all of the common stuff that we do in every application all the

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setup work all the basic things that every app needs and it just prepackage it all up so that we can

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use it and get started on new apps without having to do all the basic ground work every single time

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.

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So when we read an application we just focus on the important content of the application.

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What makes it unique.

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Rather than spending time working on the very very basic stuff every single time we make a new application

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.

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So as I mentioned Express's what were going to use Express is a framework.

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And in particular its a web development framework.

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There are all sorts of different frameworks out there.

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There are frameworks that help you make videogames or frameworks that how we make mobile apps and there

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are tons and tons of frameworks to make web applications.

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Express is one of those other frameworks that exist across all languages.

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Include things like flask for Python Django for Python rails for Ruby Sinatra for Ruby and there are

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even other Noad web development frameworks like sales.

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J.S..

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Which is another relatively popular one but Express is the one that we're going to use.

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And let me just show you before we talk about why we're using it.

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Let me go over to an application they have created.

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This is another cloud nine instance I have running and this is an express app.

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So all of this right here all of these files and directories are all part of an express application

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and by using Express I was able to focus on just writing the application code not having to focus on

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all the basic legwork of creating a server and dealing with routes and connecting to a database and

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all the basic steps that every app requires instead of just focused on the application content.

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Shortly we'll be creating our own apps that look like this where we have 20 30 different files in 10

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or 15 different directories all sorts of different packages that were installing and including There

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will be tons of moving pieces but Express is the glue that keeps everything together.

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What I'm saying will make a lot more sense once you actually start writing apps and the next video and

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you see what Express actually does for you.

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So the one other thing that I want to talk about is why are we using Express.

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I said there are a lot of different frameworks.

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Why are we going with Express.

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My answer is very similar to the answer I gave as far as why were learning node why were using javascript

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on the backend instead of Ruby or Python or ph P in that theres a few reasons.

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The first reason is that express is by far.

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Without a doubt the most popular node web development framework.

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It has the most downloads on NPM it has and most people contributing to it on get habbe.

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Its just the most widely used node framework which is always a great reason for us to use it not just

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because its trendy not just because people say that its good but more so because theres lots of tutorials

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and theres a big community of people who know express who are writing about and talking about it which

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is always something you want to look for when you're learning a new technology.

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And the second reason that we're using Express is a little more complex to explain a need to give you

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a little bit of backstory on the different types of frameworks that we can have.

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There are two terms that people will use to describe frameworks.

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Those are heavy and light or heavy weight and light weight heavy weight and light weight.

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Referred to how much your framework does for you versus how much you have to do yourself.

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So think of it if were talking about Mad Libs again a framework thats heavyweight really has a lot of

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text in there and just a few blanks that you feel in a framework thats lightweight has a lot more blanks

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a lot more frequently across the page where you're expected to go in and fill in your own code more

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often.

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So where express fits into all of this is that it's a very lightweight framework so it doesn't hide

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things from you it doesn't do things you don't expect it to do.

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You use Express and you know exactly what you're getting versus a framework like rails which I love

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rails by the way I'm not trashing it but when you teach people rails it's really problematic because

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it does so much for them and you can make apps fast.

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But students don't understand what it's doing because they've never seen a framework that doesn't do

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that for them.

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So I've noticed that students who learn with a framework like Rails as their very first framework a

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very heavyweight framework where they only fill in a few blanks they end up being very reliant on rails

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and they don't understand the underlying concepts and they can't work with a framework that isn't Rail's

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or at least it takes more effort for them to learn the rails way of doing things.

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So Express on the other hand is much lighter weight and that doesn't mean that it's less powerful or

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that you can't use Express to do things that you can do in Rails.

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It just means that you need to understand how things work in order to get things done in Rails.

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You can make an awesome web app without really knowing what the heck you're doing.

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So in my mind that's really the main reason that I'm teaching express Yes it's popular and there's a

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large community behind it but more importantly it's just a great tool to learn how to make web apps

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with blessing I'll do here is show you the official express home page first thing that you might notice

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is this little blurb here.

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That express is a fast and opinionated minimalist web framework for Noj Yes.

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And this word unin piñon it'd when it's referring to a framework.

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What that means is that it's flexible.

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It lets you do things in the way that you want versus rails if you use Rails Rail's it's extremely opinionated

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.

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You have to make files named a very particular way they have to go in a very particular place with Express

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.

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We have more freedom to decide how we're going to structure things.

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You can also see that we install it just like any other package and PM install Express will learn what

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the dash dash save means in the next video.

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And to finish up on here I highly recommend you check out the Getting Started Guide.

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If you have any questions and there are some other great resources on here as well including their official

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guide API reference some advanced topics that we'll talk about at the end of the course.

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The great list of resources including books and blogs some great tutorials and a glossary that will

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come back to you later in the course as well.

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All right so let's wrap this up.

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What is a framework.

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How is it different from a library framework it's just a bunch of code that someone else has written

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just like a library is except when we use a framework.

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We have less control.

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And the goal of using one is to make our development of whatever it is a game a web app a mobile application

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.

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We want to make things faster so we use a framework.

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Express is one framework for web development and it happens to be a node framework.

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There are other web development frameworks out there but we're using Express and we're using it because

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it's popular.

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Lots and lots people use it.

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There's great documentation and tutorials.

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It's widely used and supported but also and even more importantly it's a great first framework for someone

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to learn all right in the next video we're going to install Express and make our first simple application