At the moment, there's really no way to pass arguments to scripts specified in the "scripts" field with npm run-script.

I have three options, currently:

1. Hard-code the flags into the "scripts" field. This obviously doesn't cover all situations; there's plenty of situations where I want to vary options I pass to some of the scripts, or make the scripts I write more widely applicable / configurable.
2. Pack the flags into an environment variable. This isn't very composable, it's quite un-UNIX-y, and it requires me to define all of the flags in one place. (Not to mention that WITH="--debug --optimize" npm run-scripts compile just ain't very pretty. ;)
3. Wrap the script in question (if it's not my own), and query the user interactively. Again, not remotely composable or UNIX-y; and to boot, means I have to interact with the script every single time I run it.

Here's my suggestion:

• -fLGs and --flags that come after the second extant argument to run-script are appended to the string in the "scripts" field before it's run
• anything after -- is appended to the string in the "scripts" field, before it's run

Examples:

• npm run-scripts test -- something/something_else.js
• npm run-scripts a_module compile --debug --optimize
• npm run-scripts clean -- -dXf

This is completely backwards-compatible with what exists now; it does mean that we'd have to explicitly name the current module if we didn't use --, but that's minor, when it guarantees backwards compatibility.