NPM package issues commands

npm WARN old lockfile

npm WARN old lockfile The package-lock.json file was created with an old version of npm

There are several ways to deal with this:

1. Ignore it. It’s just a warning and does not affect the installation of modules.
2. Run npm ci to make sure your node_modules reflects the lock file, then remove package-lock.json, and then run npm install (with the newer version of npm) to regenerate a package-lock.json. Because everything in node_modules will meet all the requirements, the only change from npm install will be a newly-generated package-lock.json file. Commit the updated version of package-lock.json to the repo/Docker image or whatever.
3. Downgrade npm to an older version in production. Consider running npm version 6 as that is what ships with the current (as of this writing) LTS version of Node.js. In the case being asked about in this question, I imagine you can just leave out the RUN npm -g install npm@7.19.1 from the Dockerfile and instead use the version of npm that is installed with the Docker image (which in this case will almost certainly be npm@6 since that is what ships with Node.js 14.x).
4. If you want to run one command with an older version of npm but otherwise keep the newer version, you can use npx (which ships with npm) to do that. Use the -p flag to specify the version of npm you want. For example, npx -p npm@6 npm ci would run npm ci with npm version 6 even if you have version 7 installed.

npm show latest versions

npm to show latest and safe versions of all your installed packages, you can also use:

npm outdated

npm show installed package versions

to show installed packages and versions

npm list for local packages or npm list -g for globally installed packages.

You can find the version of a specific package by passing its name as an argument. For example, npm list grunt will result in:

projectName@projectVersion /path/to/project/folder
└── grunt@0.4.1

Alternatively, you can just run npm list without passing a package name as an argument to see the versions of all your packages:

├─┬ cli-color@0.1.6 
│ └── es5-ext@0.7.1 
├── coffee-script@1.3.3 
├── less@1.3.0 
├─┬ sentry@0.1.2 
│ ├── file@0.2.1 
│ └── underscore@1.3.3 
└── uglify-js@1.2.6 

You can also add --depth=0 argument to list installed packages without their dependencies.