The documentation has been updated. My answer has substantial changes vs the accepted answer: I wanted to reflect documentation is up-to-date, and accepted answer has a few broken links.
Also, I didn't understand when the accepted answer said "it defaults to node server.js". I think the documentation clarifies the default behavior:
npm-start
Start a package
Synopsis
npm start [-- <args>]Description
This runs an arbitrary command specified in the package's "
start" property of its "scripts" object. If no "start" property is specified on the "scripts" object, it will runnode server.js.
In summary, running npm start could do one of two things:
npm start {command_name}: Run an arbitrary command (i.e. if such command is specified in the start property of package.json's scripts object)npm start: Else if no start property exists (or no command_name is passed): Run node server.js, (which may not be appropriate, for example the OP doesn't have server.js; the OP runs nodeapp.js )package.json in the directory where you run npm start, you may see an error: npm ERR! enoent ENOENT: no such file or directory, open '.\package.json'