Node is a server side version of Javascript. NPM, Node Package Manager, allows us to pull in useful frameworks, libraries, utilities, etc. that can support the functionality we need to build.
Two examples we used are Express (Node web framework) and nodemon (utility to run and automatically restart our Node server).
If Node/NPM are installed on your computer you can start a new project using npm init from the location of where your application is located. It will ask several questions about your project. Typically you would fill in the relevant ones. You can also just hit enter and it will set defaults.
Completing npm init creates a package.json file which acts as the instructions and blueprint to build/run the project.
Dependencies are required packages to build or run the application. Use npm install {packageName} to install a specific dependency. This lesson used npm install express and npm install nodemon --save-dev.
Installing pulls the packages from NPM and add them to your project. A node_modules folder is created or added to with the code for each installed package.
IMPORTANT: You will need to to run applications in Node that are provided to you by your job. The first step after cloning from Github is install all dependencies using npm install. node_modules is not stored in version control and you only do this locally.
Why did we add --save-dev when installing nodemon?
Nodemon in particular is only needed for local development. There could be any number of local only dependencies. Look in the package.json file and you'll find it is listed under devDependencies instead of dependencies.
We can separate these types of dependencies and know which are needed and others are just for our local machines.
With a package.json one section's key is scripts. This is where you can do custom scripts and overwrite some of the built in ones like npm start. The start command is available to be run by default but you may need to do special things on startup.
Our lesson showed how we can use the nodemon package when starting to run our server and restart it on save/changes to files.
Other common ones you might see are test (built in) or build (example of a custom). Custom commands have to be prefixed with run. If there was the build command example, you would do something like npm run build.
What is package-lock.json for?
This file is generated on install that ensures each dependency is installed consistently across all environments from your local to production. You will never directly change this fle (or something in the node_modules folder).
More info on NPM commands/CLI: https://docs.npmjs.com/cli/v6/commands
Over the years I've consistently run into times where the dependencies have some kind of issue. The simplest way to typically attempt to solve those issues is by deleting node_modules and re-running npm install.