Pass args into an NPM script

npm-script-args.md

Passing args into an NPM script

(According to the gospel of Tim Leslie)

Example

$ "start": "/bin/sh -c 'cd projects/${1:-$0} && yarn start' basic"

Usage

$ npm run start basic

Notes

• ${1:-$0} <-- This says “use $1 as the project directory if given, otherwise use $0”.
• Adding basic to the end of the command ensure that $0 is always basic and then $1 will always be whatever the user types on the command line. e.g. bolt start login => $1 = login.
• We can’t use ${0:-basic} to get the defaults, because if the user doesn’t supply an argument, rather than $0 being unset, it gets set to /bin/sh, which doesn’t particularly help.

Some light reading: http://wiki.bash-hackers.org/syntax/pe#parameter_expansion