README.md

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In this lesson, you will learn about the package.json file and why it is the basis of any Node.js application.

Any Node.js project or npm package is built around the package.json file. It stores project information describing the details of the project and its dependencies. It is made up of a single object in JSON format that stores information in key-value pairs.

There are only two required fields: “name” and “version”, but it's a good idea to provide additional information about your project that fellow developers might find useful.

Creating a new package.json

Let us start by creating a new folder for our application. Let us call it 'my-node-app'.

While in your Terminal, navigate inside your application folder.

cd my-node-app

Next, we will create a new package.json file for our application.

We have two options to create a package.json file.

1. Create a new file called package.json and manually enter the configuration.
2. Use the npm CLI that we discussed earlier to generate one for us automatically.

In our scenario, let us use the second method to create one.

In your Terminal, while inside the application folder, enter the following command.

npm init

It will execute and ask for a few details to create your package.json. First input the name of your package, in our case my-node-app and press enter.

The "name" field contains your package's name, must be lowercase and one word, and can contain hyphens and underscores.

Next, the CLI asks for the version. Just press enter as it will take version 1.0.0 as the default version number for your application.

Next, we need to enter the description of the application. We can input My first node application and press enter.

Next, the CLI requires us to provide an entry point, which is the file which gets executed first when this application is run. Just press enter to default it to index.js.

Just press enter to the set of questions asked next as they are not mandatory requirements for a package.json file. These can still be updated at a later point in time.

After the last Enter is pressed, the npm CLI creates a base package.json file and shows a preview of the file on the Terminal window. If we are sure about the changes just type in yes on the terminal and press enter.

The CLI creates a new package.json file with the details we entered above.

We can go to our application folder and open this package.json file created in the code editor we use.

Following would be the details of the file we just created using CLI.

{
 "name": "my-node-app",
 "version": "1.0.0",
 "description": "My first node application",
 "main": "index.js",
 "scripts": {
   "test": "echo \"Error: no test specified\" && exit 1"
 },
 "author": "",
 "license": "ISC"
}

Setting defaults to package.json

You can use config set commands to configure the default values that a new package.json starts with. Run the following on the terminal using your name and email address:

npm config set init-author-name "Jane Doe" --location=global
npm config set init-author-email "[email protected]" --location=global

You can test whether these settings have been accepted by running:

npm config ls

The output should contain the configuration settings you just added. Now, when you run npm init inside a folder, the generated package.json file will list your details as the author.

We will learn more about the other options on package.json, which we will use, to configure what dependencies are used and how the application runs in the following lessons.