ExpressJS - Environment

To get started with developing using the Express framework, you need to have Node and npm(node package manager) installed. If you don’t already have these, head over to Node setup to install node on your local system. Confirm that node and npm are installed by running the following commands in your terminal.

node --version
npm --version

You should get an output similar to:

v5.0.0
3.5.2

Now that we have Node and npm set up, let us understand what npm is and how to use it.

Node Package Manager(npm)

npm is the package manager for node. The npm Registry is a public collection of packages of open-source code for Node.js, front-end web apps, mobile apps, robots, routers, and countless other needs of the JavaScript community. npm allows us to access all these packages and install them locally. You can browse through the list of packages available on npm at npmJS.

How to use npm?

There are 2 ways to install a package using npm: globally and locally.

• Globally: This method is generally used to install development tools and CLI based packages. To install a package globally, use:

  npm install -g <package-name>

• Locally: This method is generally used to install frameworks and libraries. A locally installed package can be used only within the directory it is installed. To install a package locally use the same command as above without the -g flag.

  npm install <package-name>

Whenever we create a project using npm, we need to provide a package.json file, which has all the details about our project. npm make it easy for us to set up this file. Let us set up our development project.

1. Fire up your terminal/cmd, create a new folder named hello-world and cd into it:
2. Now to create the package.json file using npm, use the following.
   

   npm init

   It’ll ask you for the following information:
   Just keep pressing enter, and enter your name at the “author name” field.
   
3. Now we have our package.json file set up, we’ll install express. To install express and add it in our package.json file, we use the following command:
   

   npm install --save express

   To confirm express installed correctly, run
   

   ls node_modules #(dir node_modules for windows)

   Tip: The --save flag can be replaced by -S flag. This flag ensures that express is added as a dependency to our package.json file. This has an advantage, the next time we need to install all the dependencies of our project we just need to run the command npm install and it’ll find the dependencies in this file and install them for us.
   

This is all we need to start development using the express framework. To make our development process a lot easier, we will install a tool from npm, nodemon. What this tool does is, it restarts our server as soon as we make a change in any of our files, otherwise we need to restart the server manually after each file modification. To install nodemon, use the following command:

npm install -g nodemon

Now we are all ready to dive into express!