npm is not deprecated and is a pretty good choice. pnpm is a bit nicer in some details, but it's a nonstandard tool - use it if you're familiar with frontend development enough that you understand the tradeoffs you're making, but otherwise sick with npm.
npx is a tool bundled with node/npm for running commands in isolated environments. It's mostly useful in two situations:
* You want to run a particular NPM-distributed tool as a one-off, and have the tool installed outside of your current project and then uninstalled afterwards. This can be useful for scaffolding or trying out tools released using NPM.
* You have a local project and one of the dev dependencies provides a utility to e.g. lint the code or run a migration. npx allows you to directly call commands installed locally without having to set up `npm run` beforehand.
If you don't know why you need it, you don't need it.
npx is a tool bundled with node/npm for running commands in isolated environments. It's mostly useful in two situations:
* You want to run a particular NPM-distributed tool as a one-off, and have the tool installed outside of your current project and then uninstalled afterwards. This can be useful for scaffolding or trying out tools released using NPM.
* You have a local project and one of the dev dependencies provides a utility to e.g. lint the code or run a migration. npx allows you to directly call commands installed locally without having to set up `npm run` beforehand.
If you don't know why you need it, you don't need it.