How to add a non-npm dependency to package.json?

One of the great features of the npm ecosystem is the ability to install and manage packages from the npm registry. These dependencies are listed in the "dependencies" section of the project's package.json file.  However, sometimes you may need to use a dependency that isn't available through npm, such as a library that you've created yourself, or one that hasn't been published to npm yet. In this case, you can add a non-npm dependency to your package.json file. In this article, we'll discuss how to add a non-npm dependency to your package.json file.

Features:

• Non-npm dependencies can be any library or module that isn't available through npm, such as a local library or a private repository.
• The process for adding a non-npm dependency to package.json is similar to adding a regular npm dependency.
• Once added, non-npm dependencies can be imported and used in the same way as regular npm dependencies.

Syntax: To add a non-npm dependency to package.json, you can use the following syntax:

"dependency-name": "file:path/to/dependency"

The "dependency-name" can be any name you choose, and "path/to/dependency" should be the file path to the dependency's source code. This can be either an absolute path or a path relative to the package.json file.

Note: to run the project, remember to type the following in your terminal in order to use the dependencies:

npm install .

There are a few different ways to do this, depending on the type of dependency you are trying to include. Here are the steps for adding each type of non-npm dependency to your package.json file:

Example 1: Git Repositories:  If you want to include a dependency that is hosted in a git repository, you can use the git+ protocol in your package.json file, as shown below: 

"dependencies": {
    "my-git-dependency": "git+https://github.com/user/my-git-dependency.git"
}

For example, let us create a project that uses the hashmap library on GitHub, which allows one to use any data type as a key for a hashmap object.

package.json

{
    "name": "gfg-nj",
      "version": "1.0.0",
      "description": "",
      "main": "index.js",
      "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1"
      },
      "dependencies": {
           "hashmap" : "https://github.com/flesler/hashmap.git"
      },
      "author": "",
      "license": "ISC"
}

index.js: The index.js may be created as follows.

// use the hashmap library added as dependency
const HashMap = require('hashmap');

// Creating a new HashMap
let map = new HashMap();

// Adding key value pairs
map[1] = "one";
map[[2, 3]] = "two";
map[[2, 3]] += "three";
map[3.2] = "three point two";

// Displaying the map
console.log(map)

Output:

This will allow you to require the git repository in your project to use the same syntax as any other npm package.

Example 2: Local Files: If you want to use a local file as a dependency in your project, you can add it to your package.json file using the file: protocol. The syntax is provided below:

"dependencies": {
     "my-local-dependency": "file:../my-local-dependency"
}

This will allow you to require the local file in your project using the following syntax:

const myLocalDependency = require('my-local-dependency');

module.js 

// This file provides a definition for the sum method

function sum(a, b) {
    return a + b;
}

To use this file as a dependency, the package.json may be updated to:

{
  "name": "gfg-nj",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "dependencies": {
    "sum-module" : "file:C:\\Users\\phala\\Desktop\\GFG-NJ\\module.js"
  },

  "author": "",
  "license": "ISC"
}

To test the module, an index.js file may be created as follows:

// Load the module.js file
const sums = require('./module');

// Displaying the result of the sum method
console.log(sums.sum(1, 2));

Output:

Updating Dependencies: Once you have added a non-npm dependency to your package.json file, you can install it using the npm install command. This will download and install the dependency in your project's node_modules directory. If you need to update the dependency to a newer version, you can use the npm update command. This will update the dependency to the latest version specified in your package.json file.

Advantages:

• Non-npm dependencies can be used in cases where the dependency is not yet or will never be published to npm. This can be useful for projects that use internal or private libraries.
• It allows one to use a specific version or commit of the dependency, that is not available in npm.

Disadvantages:

• Non-npm dependencies can be a source of difficulty in the development and maintenance of the project, as they don't follow the same process as npm packages.
• Managing versions and updates of those dependencies can be harder.
• It could be harder to find the documentation or support for those dependencies.

Applications:

• To use internal or private libraries.
• To use a specific version of a library that is not available on npm.
• To use libraries that will never be available on npm.
• Using pre-release versions of packages that are not ready for general consumption.

Adding a non-npm dependency to your package.json file can be a useful way to include libraries or modules that aren't available through npm. While this process is similar to adding regular npm dependencies, it's important to keep in mind that non-npm dependencies can bring additional maintenance and management challenges. Careful consideration should be taken when deciding to use non-npm dependencies in your project, to weigh the advantages and disadvantages. In general, it's best to only use non-npm dependencies when they are necessary, such as in the case of internal or private libraries or to use a specific version of a library not available in npm.