I used to put a script in each
package.json file called
dev. The idea was to watch for changes and then run tests. No need to pollute the scripts section because we can abstract it to a system wide command.
First thing to do is
npm install -g watch.
Then add an alias to .zshrc (or whatever) file:
alias dev='watch "npm test" . --ignoreDirectoryPattern=/node_modules/ --ignoreDotFiles'
Voila. Just run
dev in the target tld.