01 - npm packages

In this module, we'll set up a few of the server packages (dependencies) that will be used in this application.

Orientation

screenshot

What is a Dependency?

A dependency is a necessary requirement for a class or interface to use. Think of this analogy:

• If you have a TV remote, you also need the batteries.

• You cannot use the remote without also using those batteries.

• Furthermore, you cannot continuously reuse that remote unless you also continuously reuse those batteries.

• If your batteries fail, you can no longer use your remote.

Just like the remote depends on batteries. Your application will have other applications and frameworks (like Express) in the form of packages to rely on for it to run.

npm init

Let's initialize npm as our package manager for our dependencies. To initialize npm in the application, go through the following steps:

1. Open the server folder.

2. Open the command line window.

3. Run npm init.

4. Hit enter through all the prompts.

5. You should see a new package.json file in your server folder.

package.json

1. Take out the contents of the package.json file.

2. Replace the contents with the code below.

3. Run npm update. This will read all of the new dependencies from the package.json and load them all in the node_modules folder.

4. Know that adding these new packages to package.json file allows us to freeze the particular versions of each dependency so that they harmonize together without breaking the application. For instance, let’s say that dependency bcrypt has changed to 3.0.0 and the new version does not work well with sequelize 4.0.0. Such a change might break our app.

{
  "name": "workoutlogserver",
  "version": "1.0.0",
  "description": "server for workout log app",
  "main": "app.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node ./node_modules/http-server/bin/http-server"
  },
  "author": "YOUR NAME HERE",
  "license": "MIT",
  "dependencies": {
    "bcryptjs": "^2.4.3",
    "body-parser": "^1.18.2",
    "dotenv": "^5.0.1",
    "express": "^4.16.3",
    "jsonwebtoken": "^8.2.0",
    "pg": "^7.4.1",
    "pg-hstore": "^2.3.2",
    "sequelize": "^4.37.0"
  }
}

Project Dependencies

Here is another quick cheat sheet for the dependencies that will be used in this application.

Package	Purpose
bcrypt	Password-specific hashing that protects your password from being stored in plain text
body-parser	Parses the body of an HTTP request before it reaches an endpoint's functionality
dotenv	Allows developers to safely store configuration data
express	A web framework for Node.js that allows routing and processing HTTP requests
jsonwebtoken	A compact and self-contained way for securely transmitting information between parties
pg	A dependency for working with Postgres
pg-hstore	A dependency for working with Postgres for advanced functions with Postgres
sequelize	A tool that allows us to map models, pass data, and complete queries with a database

This just a quick overview of what these do. We'll go more in-depth on some of these packages as we build our server.