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Let's first of all understand npm a bit better,

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it's node's package manager as you learned and in the end it's a cli, a command line interface.

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We always used it from the command line from the terminal by running npm and then some command, mostly

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npm install in this course. The idea behind packages or tools like npm

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and every programming language has a similar concept you could say is that we might have some isolated

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functionality, some code that we wrote or that we came up with that does something useful,

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let's say it generates a random number.

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Now we can use that in our web application but maybe we want to use it in other applications as well

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because this isolated functionality does not depend on our business logic in the project we're creating

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or maybe we want to share it with the public.

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Well if we want to share it internally or externally, we can put it into a package with the help of npm.

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You can use npm not just to install packages but also to create and share packages through that npm

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repository which is a cloud service where you don't have to pay for where you can host packages you

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created and this is also a service where you will in the end fetch packages from with the npm install

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command.

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So in this repository which is managed globally, you'll find thousands of packages obviously and if

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you now have some node project, you can use any of that, you can use any of those packages with the npm

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install command through that cli

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and that is how you add packages to your project,

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no matter if that is a package shared by you and you can also have private repositories or private packages

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on npm

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by the way, that is something you do have to pay for but you can always use public packages and share

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packages with the public.

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That's the idea behind npm,

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now let's have a closer look at the official npm repository page and the available commands

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we can use. You can visit npmjs.com,

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that is the official page of npm

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and there you can search for packages,

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for example we could search for express here which is of course a package we used, the express framework

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and then you see all kinds of packages that kind of were found for that, maybe packages that use express,

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maybe also

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of course the express package itself.

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And if you click on that, you find some quick docs, you see the versions that were released here

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so here you can see the different versions

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you could install through npm, you can target a specific version

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by the way by going to your terminal and there with npm install, you can choose the package and then an @

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sign and then a specific version number,

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for example we could choose 4.16.3 by typing for 4.16.3

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and now we would install that version into our project. If we select no version, the latest one is picked

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by default,

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that's just a little side note. So we can see that version history,

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we can see which other packages this package relies on

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and these packages will be installed for you automatically when you install expressjs

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.

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So these will also end up in node modules as will the dependencies of these packages and that is why you

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quickly end up with a big node modules folder by the way because you have a lot of dependencies of dependencies

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of dependencies.

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You also see other things like the official home page,

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the github repository, so the repository where you can find the source code for this package and so

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on.

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So this is really useful,

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now if you want to learn more about the npm command though, so what else you can run besides install

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or how you can configure install

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for example with --save versus --save dev to install a production or a development dependency,

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if you want to learn more about that, the official docs are of course the right place. There if you

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dive in,

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you can learn way more about npm and diving deeply into that would really be beyond the scope of this

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course because npm creating and managing packages, that is a topic on its own not closely related to

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nodejs the language, just an additional feature you get for free,

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so here you can learn way more about that and here on this page if you scroll down a bit further, you'll

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also see all available commands you could run

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and then if you click on one of them, for example uninstall, you also see how you may use it.

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So here you see detailed instructions on how you may configure it, for example that you can run it

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in global mode to install a package on your system and not just in a project or that you can of course

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also install it with the --save flag save dev or save prod which is the same as just

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--save in the end,

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so there you see all the ways of configuring that or running that command in different ways

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and if you want to learn way more about that

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and for most cases, you just need npm install --save or --save dev or -g

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but if you want to learn way more, of course these official docs are the place to go.

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It is worth pointing out that you also can get help here locally, when you type npm help here,

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you also get instructions on the available commands you may run and you can also get help on a specific

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command.

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So if I run npm install --help here or just -h,

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then I see how I may run this command and also which options I have to add additional flags.

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However these are just the common options, not all options, for the full docs of course,

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you should dive into the official documentation here.

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The commands you can run here especially installing are one powerful thing

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npm allows you to do,

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you can add any package you want to your project. Another important feature is that if you click on

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using npm here, you can run scripts with npm and that generally is related to that package.json

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file you get when you put a project under control of npm which you do with help of the npm init command,

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we also use that in that course. That will ask you a couple of questions and then give you a package.json

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file which you can use to configure a project and there you can not only keep a list of your dependencies,

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you can also add certain scripts and you can run these scripts either with npm start to run the start

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script or npm run and then any script name you configured in there

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and that is very powerful especially when it comes to using npm and nodejs to build projects.

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It is something I can best show in the react application

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we worked with in this course.

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Here I am in that application and there if we had a look at that package.json file, you see that

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scripts area and there you see a couple of scripts which you can run,

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for example start with npm start but that's a special case,

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all other scripts with npm run and then for example, build or eject and then these scripts are executed.

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Now these scripts actually use a third party package,

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so a dependency which was installed, react scripts we see it here in the dependencies list and then

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that dependency holds the code that will actually do something and that is the next step I will come

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back to with nodejs being able to run on your machine and not being limited to spinning up a web server.