All Node modules must include a package.json
file in their root directory. package.json
is a simple JSON text file that defines a module, including dependencies. The package.json
file can contain a number of different directives to tell the Node Package Manager how to handle the module.
The following is an example of a package.json
file with a name, version, description, and dependencies:
{
"name": "my_module",
"version": "0.1.0",
"description": "a simple node.js module",
"dependencies" : {
"express" : "latest"
}
}
The only required directives in the package.json
file are name and version; the rest depend on what you would like to include. Table 3.2 describes the most common directives.
A great way to use package.json
files is to automatically download and install the dependencies for your Node.js app. All you need to do is create a package.json
file in the root of your project code and add the necessary dependencies to it. For example, the following package.json
file requires the express
module as a dependency:
{
"name": "my_module",
"version": "0.1.0",
"dependencies" : {
"express" : "latest"
}
}
Then you run the following command from the root of your package, and the express
module is automatically installed:
npm install
Notice that no module is specified in the command npm install
. That is because npm
looks for a package.json
file by default. Later, as you need additional modules, all you need to do is add those to the dependencies
directive and then run npm install
again.