Understanding npm Scripts and Custom Commands in Node.js Projects

When working with a Node.js project, every project contains a package.json file that records basic information such as the project name, version, author, repository, license, dependencies, and optionally a scripts object where developers can define custom command shortcuts.

The scripts section consists of key‑value pairs; keys like start , dev , run , stop can be defined arbitrarily, and the values are the shell commands that will be executed.

For example, if you have used Express before, you are likely familiar with npm start , which simply runs the command associated with the start key—often something like node ./bin/www .

However, trying to run a custom script directly with npm dev will result in an error because the command after npm must be one of the predefined npm commands; custom script keys are not recognized in that form.

The correct way to invoke a custom script is npm run dev . This works, and npm run start also works, demonstrating that the full execution of a script requires the run keyword, while npm provides shortcuts for some default commands (such as npm start ) that can omit run for convenience.

The author notes that this is a personal learning note and invites other Node developers to follow and discuss via the provided WeChat ID.